I feel compelled to address certain issues in regards to the engine but especially about oils and which ones to use. There appears to be alot of speculation as to what is causing engine failures in the hotter climates and yet for some strange reason not many people are not willing to accept the high oil temperatures as the cause of the problem. This is what it is though so just accept it. I thought I'd list what I personally have found to work just fine in the rotary engine and then allow you to judge for yourself if you agree with me.

First off my choices of oils are these:
Conventional: Castrol and Havoline. That's it. Go check out the forum at www.bobistheoilguy.com I've actually liked and used both of these oils for some time now but only recently had confirmation by others that they were very good oils.

Synthetic: Amsoil and Royal Purple. I'm sure Redline is good too but I have no personal experience with it. I am very curious to try Shaeffers as in the tests I've seen it appears to be superior to all. I'll try this in the future.

Currently in all of my cars including the rotaries I am using Royal Purple 5W20. My Honda is supposed to use 5W20 but my rotaries typically use 20W50. I still use 5W20. I have had no problems whatsoever.

For oil fitlers I use Wix. They are easy to get and they are very nice. Tests have also proved them to be good as well. I wish I could find the link right now to the test.

Now as to the whole synthetic debate. Yes I use synthetic in my rotaries. They work great. I also don't want to hear the bs about how they are or are not usable in the older rotaries but are or are not acceptable in the Renesis engines. This is a crap excuse that Mazda tried to pass off when they couldn't make up their minds what to say. Synthetics work fine (better) in rotaries. They have less deposits in the engine and resist breakdown better. Don't be afraid to use them. Alot of people do. I found a Racing Beat catalog with alot of tech tips. I thought I'd share some of them for those of you who do not have the catalog. I'm going to focus on oil. Specifically in the areas of oil types and temperatures.

Page 66. Here are 2 paragraphs from "oil tips".

"Oil temperature is critical in rotary engines. Oil temperature entering the engine should never be allowed to exceed 210*F. While many factors affect oil temperature, oil cooler size and location are very important to consider. Roughly 1/3 of all engine heat rejected via the water and oil cooling systems goes out through the oil cooler. The oil cooler should get about 1/3 of the total cooling airflow."

"Another factor that inhibits heat transfer from oil is air bubbles that become trapped in the oil. Air acts as an insulator and reduces heat transfer. While rotaries have little tendency to foam the oil through windage in the oil pan, as do reciprocating engines, air is mixed with the oil as the oil moves through the rotors. By slowing the oil down as it returns to the pan, air is allowed additional time to separate from the oil. Our baffle plate is designed to perform this function."

It should be noted that the last sentence refers to the pre 3rd gen RX-7 cars as the 3rd gen and the RX-8 have a baffle built in. Thought those 2 paragraphs were interesting. Here's some excerpts from the "oil selection" part of the book.

Page 67. "Oil selection"

"The Mazda factory does not recommend the use of synthetic oils in their rotary engines- specifically addressing this issue in the "owners manual".

In 1979, Racing Beat began testing Amsoil synthetic lubrication products. Without a doubt, synthetic oils do perform well in extreme heat (over 300*F) and extreme cold (below 32*F), but by the nature of Mazda's rotary engine, the oil temperature never exceeds 250*F without severe engine damage due to other factors. In Southern California, we have difficulty seeing the low temperature benefits: however, when we put synthetic lubricants in the engine, transmission, and differential in our IMSA GTU race car, we immediately saw what we later found to be a common result: The oil temperature dropped 5* to 10*F for the same operating conditions. This is apparently due to two factors: reduced friction between sliding surfaces, and reduced foaming. As we continued to use synthetic oil products it became clear that they genuinely reduce wear."

That should take care of those arguments.

Page 67 continued...

In the '90s we tested Royal Purple Synthetic oil. In the very first test, this oil added more than 1% HP on a highly developed race engine. Since then we have seen that improvement and more in other applications, along with the low wear and reduced operating temperatures. There are 3 concerns with synthetic oils: 1) Higher cost; 2) the fact that it inhibits break-in period (so use mineral oil during the break in period); 3) and the fact that there is the potential for problems if you change to synthetic oil after years of using mineral oil. These problems are two-fold. First, synthetics sometimes cause rubber seals to swell after years of immersion in mineral oil, and second, synthetics tend to be high detergent by their nature, so changing to synthetics after many years of mineral oil use can cause beneficial carbon deposits to be scoured away, leading to high oil consumption. We believe that these are the reasons that Mazda does not recommend synthetics- even though their race team uses them."

The interesting thing about that paragraph is that it expresses several concerns that people have. As far as causing o-rings to swell, this may have been true at some point in the past but the Renesis seals are a different compound than earlier seals and will not swell. They are more tolerant. We don't want carbon deposits. We want less of them. Don't feel they are beneficial to you. They aren't. This was referring to older piston engines that have bad seals and are only being kept alive by the sealing that their carbon deposits have. They got this way due to carbon in the first place so just don't allow them to buildup in your engine.

Here is a neat passage on page 68 under their "oil pressure and temperature adapter". This sentence is extremely relevant.

"Normal oil temperature varies quite a bit depending on the operating conditions, but usually stabilizes between 140*F and 200*F. If the temperature exceeds 210*F, reduce the load on the engine immediately or shut it off. Continued operation above 210*F may damage the engine."

Back to oils again. This time from page 71.

"Racing Beat has recommending the use of synthetic oils in rotary applications for several years. Our research has found that synthetic oils provide superior friction reducing between sliding surfaces, reduced foaming, and lower oil temperatures. We have tested several different synthetic oils and have found that while most offered improved wear and lower oil temperatures, none offered any horsepower gains... except Royal Purple!"


I've been telling people what I personally like. Now I'm backing up my reasons with proof from others. By no means am I telling you that you should absolutely do it my way. Make your own decisions. As far as the engine failure debate, this should give some people something to think about in terms of their oil temperatures. There was one preson with dual oil coolers that recorded oil temps of 240+ degrees F. He had stated cruising oil temps closer to the low 200-210 range. This peak number scares me personally but people have said it isn't a bad thing. Think again! I really wonder what temps the single cooler guys are getting? Unfortunately to monitor oil temps, you need to install an aftermarket oil temp gauge. I wish more people would. I don't have one on my RX-7 but that car has much better oil cooling than the RX-8 so I'm not too concerned. What does this high oil temp mean for everyone? It means your oils will break down faster than in most other cars. Change them often along with the filters. Also use a good oil that resists breakdown and windage to help prolong the inevitable. Use a good synthetic. You know which one I like.

That's the end of my rant for now but please everyone do some oil research and come to your own conclusions for the right reasons.

 

very good read RG, makes me want to jump on the RP bandwagon :D

but I still have 2/3 case of Castrol GTX to finish off, so I'll use those up first before I decide what to do next :p

another suggestion for those want to keep an eye on the condition of your oil: submit samples of your used oils for Used Oil Analysis regularly, the test results will not only provide factual evidence regarding how well your oil is holding up, but also offer important hints of unusual engine wear before it is too late.

think of it as blood test for you 8 :D

 

I just bought some Castrol 5W-30, thinking that the slightly higher weight would prove to be a little better with forming a seal and protection, am I wrong?

 

If I were to consider installing thermostatically controlled fans behind the oil coolers, assuming they might even fit, what temp should they be triggered? 180?

I live in Arizona, and heat is a concern here. It kills all sorts of automotive components, sooner or later.

And you make a fine case for synthetics...

 

But...but...RG, what about the ash content? What about the ash??? :D

Just kidding, but I'm surprised I haven't seen the usual chorus of responses talking about that. The only reason I'm not using Royal Purple in my 8 (I did in my ex FD) is that I (foolishly) signed up to have Mazda do it for a while, and they use whatever they use.

jds

 

I run Royal Purple in my engine (5W-20) and in my tranny and love both. One of the RP engineers (Royal Purple is located in Houston) races rotary's and has been a member of our rotary club here.

the synthetic question is a non-issue for me, but if your still worried about it, I would still HIGHLY recommend the tranny fluid.

 

rotarygod; excellent post, very informative and you obviously know your stuff; i will be topping my new rx8 off for the first time soon and am concerned about oil; would you suggest castrol gtx 5w20?; i bot a bottle to have on hand and could not find any other 5w20 at my local auto store;
i live on the east coast of canada so heat is only an issue for june/july/aug and its mostly humidity;
i plan to change my oil every 5000 kms anyway so do i really need to be worried about heat or oil breakdown?; pls advise; thanks
michael

 

a) Be extremely careful of what tests you believe on that site. He mostly takes industry tests, strips out most controls to eliminate variables, and then posts results he likes. That, or he uses industry tests that have been proven to be unreliable/unrepeatable and runs them until he gets the desired results.

b) Watch out for AMSOIL. Not all of their oils meet industry standards (look for their seals) because of exceeding the recommended amounts of anti-wear additives which will act like a poison to your catalytic converter.

c) I'm not going to get into an oil brand debate, but the joke around the industry was always "Damn I wish we had Castrol's marketing ability"... [i think you can figure out where this is going]

d) Yes, synthetics will survive much longer then conventional oils in extreme circumstances. They are pure and free of contaminates which allows for more stable additive packages. The ONLY things they fail to outperform regular oils is against oil foaming since the pure oils foams more then dirtier oil (to an axtent) - this is fixed with an additive package but at the cost of a slight decrease in air retention performance.

e) Yes, synthetics have a more robust seal swell additive package. The intention being that seal swelling will decrease the chance of leaks. Conventional oils also have these additives but are not as strong.

f) Synthetics are not more detergant based in nature in the sense that it will break down formations like dish detergant in your dishwasher. They can simply suspend much much more dirt in the oil - so they will have no problem taking care of combustion leftovers but also can suspend dirt already building up and over time can clean things up.

g) The purity and robust additive packages will reduce friction/wear and give a 1-2% increase in power (not advertised in most cases for legal reasons since thats in the margin of error of most dynos and its impossible to feel) and lower temps. My experience is most of the synthetics can take almost 300 degrees F until the additive packages break down (the oil itself can take much much more). Their response to temp swings is also less pronounced then conventional oils.

 

Why is it that some owners believe they know more about what oils
should be used in Rotaries and that includes RENISIS than the
Mazda (Japan) factory who have been developing the rotary for
over 40 years.

Mazda Japan and Australia still to this day do not recommend
the use of synthetic oils in their rotaries, 8 included.

And yes we sell ALL synthetic oils here too.

The main structural design of the RENISIS is basically the
same as the13B used in the RX-7, the RENISIS
exhaust is ported via the intermediate housings rather than
the rotor housings, and no turbo.
There are minor modifications to the apex,corner seals, but
the fundamental design remains the same.

The rotary is designed to burn oil to lubricate apex seals,
corner seals, rotor side seals, and this is done by the
metering oil pump. The ability of synthetic oil to burn in
the rotaries combustion process without leaving unwanted
residue build up is another concern.
There is also a Mazda factory(Japan) bulletin to parts
departments concerning the effects on the
oil control ring "O" rings which are made of a synthetic
type compound, these O rings dissolve over time
when used in an engine that has synthetic oil.

Although the part number of the O ring in the 8 is different.
Mazda Japan has yet to approve the use of synthetics in
the RX-8, and until they do I would not use any brand.

I don't care what Bob the oil man, or racing this or that says,
I will go by what the manufacturer says.

I wonder if synthetic gas (petroleum) was available would you
use it over mineral gas even if it was not recommended.

Don't get me wrong, I am not against the use of synthetic oils
in conventional combustion engines, I am at this stage
against the use in all Rotaries.

And yes, some racing teams use synthetics in their racing
rotaries, but they rebuild them very regularly.

 

I hope this post won't come across as harsh but I really do have to address ignorance in such a way. Please don't let this mean that I am saying absolutely use only what I use. I'm not saying that. There are many beliefs out there and many preferences and oil choices to use. I really just want people to understand the myths vs the facts of oils in rotaries. Sadly I haven't completely succeeded. My original post even dispelled all of the comebacks in advance and we in fact did see them again but I'll address them again anyways.

It's funny how no one believes the manufacturer when it comes to the power ratings of their cars or what they say in regards to why there have been several engine failures yet they subjectively believe them when it comes to oils and recommendations. Oh how funny double standards truly are! Irony at it's finest.

Your concerns for the o-rings is unfounded. They are not an issue. That may have been true 30 years ago. I believe I already stated that and shot that argument down. So you are saying that until they prove them safe, they aren't. I say that until you prove they aren't, they are. Have fun trying!

I believe I also originally stated why Mazda probably recommends only conventional oils in the rotaries. It's pretty safe to say that there isn't a person here that needs an education as to how the Renesis is different than the 13B and how it uses oils. Apparently there are some though that need one in terms of what works well though.

As far as synthetic gas, I'm a proponent of converting existing cars to other fuel sources such as ethanol so yes I would use it. Yet another invalid excuse.

Why do some owners feel they know more about oils than Mazda? Who said we did? No one made that claim so why the harsh accusation? Why do you think you know more than the people with synthetic experience? Especially when you only believe what the manual says and have no experience with it in rotaries personally? Synthetic oils are perfectly safe in the rotary. Use what you want. It's your car. It doesn't bother me. Just change your oil and filter often. I also showed what conventional oils I like as well. Why is it you won't believe the experts on oil such as at bobistheoilguy.com? They've got alot of facts over there and test results. Strangely enough people think they are only giving the wrong data to skew the results in their favor. (That's how I feel about democrats btw but we won't go there as that too is just an opinion!) Mazda builds cars. That's it. They don't build oils or spend their days testing them coonstantly. If they did, they'd recommend synthetics as well. What gives the person with zero synthetic experience at all who isn't willing to listen to actual real world proof the credibility to question anyone else who does?

This wasn't a thread intended to convert people over to synthetics. It was a thread that was intended educate many people as to what actually can and can't work well in the rotary and to put to rest the unfounded excuses not to use it. It doesn't mean that you have to use synthetics in them. Sadly though there are always those stubborn few that require far more than proof and the approval of the entire world before they will believe it. I've been using synthetics in 2 rotaries now for seveal years. No problems whatsoever. I also use 5W20 in my rotaries. I use this weight in older rotaries that are supposed to use 20W50. No problems whatsoever. Alot of my friends use it. Alot of others that I know of use it. The founder or Royal Purple is a rotary guy. He uses it. There are many with real world experience that count for far more than what someone says on paper. I wonder if I should write it down and publish it somewhere? Hmmm...

BTW: The argument that race cars change their oils all the time is also irrelevant. They also use lower detergent oils than street cars but they have higher lubricative properties. Yes they change their oils all the time. They also need their engines to perform at 100% perfection for the entire race. Sadly it's far less important for power to fall off in a street car than a race car. It is also more common. You show me a race team that doesn't care about engine longevity and uses an oil based on this belief and I'll show you a losing team. Typically rotaries can run for a couple of seasons before being rebuilt and even then show little signs of wear. Since 100 miles of track use is harder on the engine than 1 mile of street use, that is significant. Can't tell me they don't know what works best.

Why do I think I know better than Mazda? I don't think that. I do think that real world experience and results means far more than what they say though, especially when their hardest used rotaries also use it. Does anyone here think they know better when it comes to intakes, exhausts, ignition systems, porting, tires, suspension, etc... than Mazda? That must mean that only the car in it's pure stock form is truly the best and that there is nothing better that can be done to it because Mazda doesn't say it is OK. See how ludicrous closed minded thinking is?!

Rant over. This still doesn't change the fact that everyone should use what they personally like synthetic, conventional, or otherwise.

 

Want to point out again the Warranty issue in all of this.. If we fall victim to one of the engine failures, or any number of possible engine problems, can our use of Synthetic Oil be used against us by Mazda when it comes to Warranty claim??

 

RG, thanks for the good info, both posts! I read all of the synthetic vs. conventional oil threads before buying my 8 in Feburary. I have chosen to use a synthetic in my rotary. I've been sold on some of the advantages of synthetic for a while. Although I watch the odometer, I prefer to monitor the oil by look and feel. A day on the track will suspend an amazing amount of byproducts in the oil and my brain says "change the oil" even if its only been in the oil pan for a few hundred miles. I use various brands and grades of synthetic in all my my engines (3 cars, 1 RV & 3 motorcycles).
From working with production as well as R&D folks in various industries, I feel totally comfortable 'modifying' the manfuacturer's suggestions. I feel most of them are based on advice of lawyers and bean-counters, ~maybe~ ignoring input of the actual test results and technicinans.
If we all listened to everything we were told no one would belive the world was round, the moon wasn't made of cheese, no one would have ever tried to fly and the rotary engine would never run. Additionally, if I believed everything posted here I would have convinced myself that my rotary would have flooded the first time I tried to crank it....
Apparently the oil debate continues....

 

If you had an engine failure, would you really tell them you used it? You won't have an engine failure from it anyways but when a problem arises it is best to not divulge any information than you have to. If they ask you if you are using synthetic, say "no"! If you go in for a transmission problem and they ask you if you have been racing, you would probably say no also, even if you had been. They don't do an oil analysis and won't know unless you told them.

 

For the first 6 months of owning my car we had to use a synthetic oil as Mazda japan had no mineral oil available for our cars Downunder

Its friggin two years down the track and no one knows the real answer to this dilema synthetic or mineral oil ??

All i know is if anything ever goes wrong with my engine that i can relate to wrong oil usage mazda lookout .

Releasing a car for sale knowing that the correct oil is not available for the consumer and knowing that using a synthetic oil could cause long term harm to an engine is negligent

B...free
michael

 

RG
are. Have fYour concerns for the o-rings is unfounded. They are not an issue. That may have been true 30 years ago. I believe I already stated that and shot that argument down. So you are saying that until they prove them safe, they aren't. I say that until you prove they aren't, they un trying!
Wrong RG
The Factory Bulletin concerning the oil control "o' rings was 2001 for memory, not, 30 years ago.
So you know more than the Factory.

RG
I believe I also originally stated why Mazda probably recommends only conventional oils in the rotaries. It's pretty safe to say that there isn't a person here that needs an education as to how the Renisis is different than the 13B and how it uses oils. Apparently there are some though that need one in terms of what works well though.

From what I have read in many post, some believe that you cant make any comparison between the Renisis and previous rotaries. The way it uses oil is exactly the same as all rotaries.
The oil control rings and O rings are the same for all rotaries, but their interchangeability, ie replacement parts, new mods replace old, but old cant replace new, so the oil ring sold in the Bathurst RX-7 sold in Japan until 2002 can be used in an R100,RX-2,3,4 and 5. So that "O" ring technology is not 30 years old...
RG, do you know what the "O" rings function is and where and how they are installed.

RG
As far as synthetic gas, I'm a proponent of converting existing cars to other fuel sources such as ethanol so yes I would use it. Yet another invalid excuse
Here in Australia we have Ethanol plants, the Ethanol is refined from sugar cane, so its not actually synthetic.
At the moment it is available at a 10% blend.
Many car manufacturers here do not recommend it, and even Toyota will void warranties because the ethanol can corrode fuel lines in certain models and the same applies with Mazda, Again Mazda does not recommend ethanol blend for the RX-8, but its OK in others... www.mazda.com.au

As far as RX-8 Engine failures in the US are concerned, it is yet to be confirmed what is the cause(s).
The factory will investigate from returned engines... My guess is a combination of heat and the oil viscosity/protection, particularly if the oil has lots of use (Mileage).

RG, I respect your opinion.
It is very easy to insult someone when you don't believe their views, when in many ways its that person ignorance that is the cause.

Owners will do as they wish, in the interest of protecting a new vehicle warranty, I will do what is recommended by the manufacturer until further notice.

And please don't underestimate what a vehicle manufacturer will do when testing what
products are suitable to put into their financial development/investment.

They do a lot more testing of their cars all over the world before production.
Sure something's are overlooked, but you cant overlook the stupidity of some
owners who fail to add any oil at 10000 miles and their rotary cooks, or, cooling system is damaged by a rodent and they keep driving when warning lights are flashing, or the owner who continually fails to engage their clutch when changing gear, crunching the box time and time again.
But the manufacturer is the biggest *** hole out, has a defective product.etc, etc, etc.

When you work in a retail dealership for many years you see them all, the overwhelming catastrophic problems in many cases are the owners fault...not all though.

I guarantee not all of the post here in this forum about owners and their RX-8s faults are telling all the story (truth).

 

Lock and Load

Hi Michael...

Why did you guys not use Castrol GTX2 or GTX3, in Australia both of those are premium mineral, GTX3 is 15w40, and I think Ideal for the 8.

I heard the Mazda Rotary oil here is Castrol repacked for dealers?

I have a mate that I once employed who now works at City Mazda- Adelaide,
he has been at Mazda Parts for 30 years, so he tells me about the oil.

A 40 weight would be fine for summer, and 15, for winter.
we really dont have zero temps, unless you like around MT Buller!

Cheers

 

So you just called Rotarygod ignorant?

And: you have yet to actually prove anything, with real data.

I hope everyone else can see exactly how this person is spouting mindless dribble.

Don't do drugs kids, they ruin lives.

 

Gracious, can't we all just get along?

 

RG

Do you think it telling demob05 to lie if they used synthetic oil would do any good.

I can assure you that if their engine was replace under warranty the engine will
quickly end up in Japan and everything including the oil will be tested.
The factory knows exactly what car and who the owner is.... great if the dealer is aware you
lied for any future servicing or repairs on your car.

Perhaps in the States you think car salesmen are con artists to get the sale, we have them here too in OZ.

But the guys in Service and Parts are generally very helpful and fair, they are not con artists, they know the product far better than any car salesman.

A good relationship with the Service and Parts guys will go a long way.

 

What data would you like staticlag
Would you like more dribble......
Please what an experienced attitude you have...

 

It might be worth mentioning that ASH8, at least according to him and I have no reason to doubt him, is a former Warranty Claims Officer for Mazda.

So take that for what you will. The experience is there, just a different kind

 

I am unsure about the oil control ring failures being caused by all syth oils, IIRC it was more specifically linked to the MOBIL 1 Syth formulation of the time. (I could be wrong, though) But moreover, If one were to suggest ash build-up as a byproduct of using sythetic oil - a "purified" oil - how does one explain a more complete oil combustion from oil that has crude elements, such as wax and likely a higher sulfer content? Such nasties do not burn well either. Just a thought...

 

I am really reluctant to post this...because of all the cynics out there.

Yes, I worked for Mazda for more years than I can remember...well almost.
1970s
AT 17, I started at a Mazda dealer in a parts department that did not exist, I did
all the odd jobs, even warranty claims, then claims were hand typed onto claim
forms. The amount of rotaries we did for coolant entry were many. Mazda had
an extended warranty I think it was after two years up to 4 they paid for parts, owner
for labour. I was continually liasing with the service manager. I saw dozens of rebuilds.
They are etched into my brain..all the part numbers....for R100, RX-2,3,4.
From about 1974 the 13B came out, from then on coolant entry was not a problem,
the RX-5,7s were very reliable.
AT 19, I started to build the parts dept, employed staff, eventually building the most
successful retail Mazda parts dept in the state, winning awards and a trip to the
factory at Hiroshima in 1980 or 81..cant remember.
I went to Mazda (SA) wholesale for a few more years, then back to retail, and
then into Service Department in the early 90s as a service advisor.
I am now 48 and no longer in the car industry because of my health.
So there you go.

 

No one advised us that the Castrol GTX2 - GTX3 could or should be used ,instead we used the normal castrol 5-w30.

I constantly asked mazda Australia when the mineral oil was coming and as ussual they knew jack **** .

.I have documented the usage of the oil not recommended by Mazda so if i have any problem down the road i should be covered .

B...free
michael

 

You wont have any worries with the "mazda oil", or warranty coverage issues.
Cheers