nycgps

iTrader: (1)

Lemme add some oil to fire ...

- Engine bearing is the same for 20-30 years, even Renesis. Yep, I am using RX-8's Bearings to do a RX-7 FC rebuild. because it's heat treated at factory, but most important thing is that it's cheapest and the strongest.
- Older Rotary engine use much heavier oil, at least 5w30, but most people use at least 10w40. Never seen any problem with bearing wear.
- 5w20 oil in Renesis, highest NA engine output. so much wear. Same engine, heavier oil, not so much wear. Isn't that enough to tell to people something is wrong with the oil choice ?

Every component has a "designed life", Like the Clutch Pedal, Mazda said it's "design life is 10 years or 100K miles" but OBVIOUSLY this is far from true. They designed the car and I'm sure all of them have an engineering degree, right? what happen ?

5w20 is great for MPG and "good enough to last till the warranty is over" and that's it.

Good thing about the bearing is that, it might be WAY out of spec (I seen it myself) but your engine might still operate normally, until one day it wears too much And throw everything out of balance then the apex eats everything alive.

My Father's CX-7, a Turbo charged engine and they want me to use 5w30. yeah right. 10w40 or 20w50 all it's life.

nycgps

iTrader: (1)

as long as it's sealed. it will still be ok.

paimon.soror

iTrader: (15)

yup, sealed, thanks i will try and send it in asap, i am interested in seeing what the results are since I started using the rp @ 3000mi

40w8

I've seen enough weird oil recommendations for various machinery to realize that engineering the total use of the product is difficult.

The operator has to understand the machinery and the operating conditions to apply the correct oil and other products.

Input from extreme users on this forum is free R&D, and I'm still sold on nothing less than Xw40 for the rotary or any engine that you redline.

ZeroKunoichi

That is why I posted my environment and driving conditions. I am a pretty casual driver a rarely redline my car either.
I know that there are 2 versions of the RX-8 the S1 and S2 and the S2 started either '05 or '08 I am not sure on that one.
Me driving in Arizona is different from someone driving in Washington or New York.
If everything in the US has the same conditions for driving then "yes" you can use what is given to you in the handbook.
It's like building a computer and then asking yourself what type of computer you need to build to suit your needs.

Gaming, Browsing, Production are all different and require different computers with different components for their individual performances.

I don't know why there is a huge debate on this when the same concept can be applied to regular basic science here.

usnidc

I am not an engineer or Lubrication scientist, but from what i have read on BITOG and other places, don't we want oil to get to all our important parts fast, therefore a low cold number, i.e a 5wXX or 0wXX, year round? If you get in the 10wXX or 20wXX the oil flows slower at startup and your bearings and apex seals would be LESS lubricated until the oil is closer to its normal operating temps. Of course, all manufacturers will have slightly different viscosities and flow rates so if you wanted to get really **** about it you'd have to look at the spec sheets for the specific oil you want to use.

I would think optimal for the engine for daily driving would be a 0-5w30-40 type oil depending on your local weather conditions. Tracking your car would obviously necessitate different weight oils.

if you are really worried about your engine or drive fairly aggressive, a good 0w40 oil, in my opinion, would be a good bet.

Now, in my 1979 RX-7 with 150,000+ miles on it, I use 20w50 because I am trying to make it last until i can get it rebuilt and I rarely drive it.

paimon.soror

iTrader: (15)

The idea of "lower is better" doesn't work with motor oil. Depending on where you live, you can throw a 0w in the motor, but because your outside temps never get low enough, the oil's weight could be sitting at a 10w equivalent. To most that really doesn't mean much, but once you get into the shear strength and properties of a good 0w against a good 10w, you could be passing up on some of the benefits of using teh 'right oil' for teh climate

olddragger

iTrader: (3)

just to help remind folks-----its not the viscosity that is important--its the film strenght. Now those two in many casual conversations are used symbiotically, but do please remember that is not neccesarily true.
I have always believed that an engine oil temps should be basically the same regardless of the season or the ambient temps? If there is a great deal of a difference then the cooling system needs work? Driving style does affect oil choice, but not the need for a certain film strenght. That is determined by engine tolerances, bearing temperatures and power output.
It gets complicated! Therefore I just recommend either a diesal synthetic 15/40 if you keep your oil temps at the filter below 220F. If not then I recommend a gasoline synthetic in the 20w 50 range. Extreme climates excluded once again.

9krpmrx8

iTrader: (46)

You would know man, I doubt anyone else on this board has as much experience in the oil/gas industry as you do. When the hell are you going to be stateside anyway?

nycgps

iTrader: (1)

YOU ARE WRONGGGGggGGgGGgg !

According to some of the "experts" here onboard. Mazda designed the engine so they know best ! 5w20 is the way tooooooo goooooOOOooooo ! They have engineering degree I don't ! no one other than Mazda should recommend ANYTHING ! no matter how many messed up bearings people saw cuz the owner was using 5w20 !

...

*silently pour some 20w50 into the engine ...*

paimon.soror

iTrader: (15)

did we have an OA on similar brand 10w-40 compared against 20w-50? I have a case of RP 10w left for this year and next, but I am interested in the claims that 20w is even better, just wanted to compare numbers

renesisking

iTrader: (1)

I've used 5w20 throughout the entire life of the car. I had the engine replaced a long time ago, I still haven't gotten a decent explanation from the dealership, and still continue to use it. So far on this new engine its been fine. I haven't had any complaints however after I autoX I noticed that I went through oil a bit more and my coolant temps typically reached 220F. On highway cruising the temps don't pass 190 on a hot day and in the winter are around the 180mark. I haven't had the time to test the difference between weights but I accidentally got 5w30 and noticed no difference. I use dino oil and not synthetic. So far, like I said no issues. I've used Mobil Clean 5000, Castrol whatever, Quaker State, Pennzoil and found no difference in feel and I don't think I will feel a difference. I haven't been able to track my car because of my hectic schedule this year but if I do I'll have to try a higher weight so that I have more protection in the higher revs. I am a bit tossed up on which weight I plan on using so I have to read up a fair amount when I get the time.

bse50

uh...

Nadrealista

The only 5w-20 oil I would put in my car would be Redline 5w-20 with HTHS viscosity of 3.3 which pretty much gives you a protection level of a good 5/10w-30 syn oil...this would be sufficient for daily street driving but on the track you want oil with HTHS north of 3.5

40w8

As they say here: "God willing, next thursday."

Nubo

Very, very simple answer: It doesn't matter.

40w8

If you want teh right weight all the time, keep your car heated to 150 degrees, and run a straight SAE 40.

For others that like more convenience, a 0w40 is about the same thickness near freezing as a 10w30, but stays thicker at ALL hotter temps like the 40w it is.

40w8

Exactly!

A guy over on BITOG suggested that you could buy one of every MO on the shelf, and put 4 or 5 different oils in at every oil change.

He's right!

Almost every engine would be fine except some of those German car "sludgemonsters".

We all have some of the hard to lube machinery: transmissions.

I've seen other manual trans use SAE 50 (appprox weight of 90 gear oil), 220 gear oil ( SAE 90), 20w50, and even some use ATF.

And of course, you better get the ATF right in your auto trans, but picking MO for your 8 is a lot easier than your wife or gf picking her face cream.

Flashwing

You need to go back and either read or re-read the information that brought you to this conclusion. The "0W" measurement of oil is totally meaningless.

Here's something that will blow your mind. Do you know what the difference in viscosity is between a 0w50 and a 20-50w when the oil is at 212 degrees of operating temperature?

ZERO!

With the exceptions of manufacturing differences that provide small variations in Cst, the actual weight of the oil (20, 30 etc.) is all that matters.

So what importance does the initial measurement serve? It simply tells you how close or far the viscosity is when the oil is cold and when it is at operational temperature. A 20w-50 is much closer to the operational CsT of a 50w than it is with a 0w-50. If you look at the actual information for motor oil it will show you what the CsT is for 70 degrees and what it is for 212 degrees. That's why it is referred to as a "multi-viscosity" oil.

Frankly, everyone should use a 0w oil. This is because the most amount of wear on an engine happens at startup while second in line would be at shutdown. Reason being is there is zero oil pressure at startup while there will be falling pressure during shutdown. You want your oil to flow as close to the operational CsT as possible when the engine is cold.

The notion of using a "winter" and "summer" oil is also totally bogus. Why? Because the interior environment of your engine does not change with the seasons. I can tell you that the difference in operating temperature between 50 degrees in Phoenix winter and 115 degrees in Phoenix summers is about 10 to 15 degrees operating temperature. A 65 degree swing has very little effect on how your motor really runs at cruise or on the street. Now, if you have excessive oil temperatures beyond the 212 degree rating on oil then you need to look into oils that thin to the necessary CsT that the rotary engine requires at your expected temperature.

I know I've posted this in various discussions of viscosity so if you're truly interested spend a few hours searching this forum and you'll find a TON of information on this topic.

In regards to "lower is not always better" you are slightly right and mostly wrong. Google the Stribeck curve and once you wrap your head around it you'll see what I'm saying. The curve shows the coefficient of friction based on load and RPM. You can see how viscosity and rpm have a direct impact on the CoF as well as the region of lubrication. You'll see that there is a sweet spot with lower viscosity oils that produce the maximum amount of lubrication (hydrodynamic) with the lowest amount of CoF. So lower is better. However, you can see that higher viscosity still provides hydrodynamic lubrication but as the rpm increases the CoF goes up.

Why? Because the increased viscosity creates drag over the metal surfaces. This will create excess heat as well as increase drag on the motor. Not really a problem for street cars but for NA race cars you can clearly see a critical HP loss simply because of fluid viscosity.

Now of course this isn't taking into consideration the aspect of pressure regulation with the RX8 which adds a whole other variable with oil performance.

99.9% of you out there don't need to be concerned about oil because you are not pushing your car in any manner which will be made or broken by your fluid choices. However, for those who are looking for every inch of performance this science is very important.

Either way, while it might not change your oil choice at least you can be part of a small fraction of drivers that understand WHY you buy the oil you do. No one else does.

You all need to do some heavy heavy reading and all the information you need is on this very forum.

paimon.soror

iTrader: (15)

I appreciate you taking the time to type this up, and although your post will encourage me to do some more reading, there are a few points you make that arent really clicking...


The confusion is this .... at the beginning you mention that the 0w measurement doesn't mean much ... which makes sense as all oils are different and no Xw's are created equal.

Next, you state that the 20w is closer to the CsT of a 50w than a 0w...

Lastly you say that you want your oil to flow as close to the CsT as possible when cold...

And then you mention that everyone should be using a 0w

I am not sure if you were trying to make an intellectual effort to debunk my knowledge of oil, however limited that may be, but it doesn't seem like the point you were trying to reach was done effectively

Flashwing

Ah you're right, sorry for the mistake. Allow me to clarify.

First, the lower the CsT the lower the viscosity of the oil.

We'll use a 50w as the example. Let's say for the sake of argument the CsT of 50w is 150 at room temperature. This is referred to as a "straight 50".

In this case, a 20w-50, might have a CsT value of 120 at room temperature.

So the 20w-50 will flow better at room temperature than a straight 50. However, a 0w-50 might have a CsT of 100 or maybe lower at room temperature.

Now remember that the operational temperature of a 50w oil is probably 18 to 20 CsT at 212 degrees.

So to wrap this all up. You want your oil to have the CsT (Viscosity) while at room temperature as close to the operational temperature CsT as you can. A 0w-x oil will be much closer than a 10w-x or a 20w-x.

This is why I say the initial number is meaningless. You might think that a 5w-50 and a 5w-30 have the same cold viscosity but they don't. It simply reflects the variation in CsT at room temperature between a straight weight oil and a multi-viscosity. The rating system really does suck and is highly confusing which I think is almost completely a marketing strategy.

So why do we have these other choices? Why not just use a 0w oil? The reason could be due to the additives in the oil. Motor oil doesn't naturally behave this way, it has to be engineered. Additive packages are put into oil to limit the viscosity increase of oil as it cools. These additives wear out over time and it takes more additives to make a 0w oil behave as it does than say a 20w oil. Over time as these additives wear out your oil will begin to behave more and more like a straight 50 weight at room temperature.

Remember, at operational temperature none of this matters as oil behaves the same way when warm with regards to viscosity.

If your target CsT is 15 which is about the CsT of a 40 weight oil then you want the oil to be as close to that as possible when cold so it flows better. A 0w oil will do that for you better than a 10w oil.

Remember too that sometimes a 5w oil will have the same cold CsT as a 0w oil but simply has a lower pour temperature.

I think I got mixed up in my previous message so I hope that clears it up.

The above doesn't really debunk your point. The information regarding the stribeck curve addresses that.

Flashwing

Main thing to keep in mind is oil choice is very personal. There is no other product for a car that has as much emotion and "feeling" associated with it as motor oil. There are very scientific reasons for choosing one oil over another but most people lack the necessary information to make an informed decision. This also includes how the oil behaves inside their motor.

People buy expensive, exotic oils simply because it makes them feel good. It could be they believe it protects their motor better or it handles their punishment of the car. The truth is that the API standards of oil are very high today and even the most inexpensive oils that meet these standards are good. The newest API standards are even more strict requiring oil to undergo punishment that should never ever be seen with a car.

In the end you'll find your reading won't sway your opinion too much on what oil to use but you'll be able to make that decision with confidence that you could explain it to someone should you be asked. Everyone else will say "because this oil feels better".

paimon.soror

iTrader: (15)

You are the man, again thanks for taking the time to type this up, hope you know that I wasn't trying to start an oil debate, but just trying to learn for my own knowledge and to make sure that I wasn't uber confused. Thanks again

Iluvrevs

This is a very good discussion with the exception of the bolded point above from my education on the matter. It would actually be in reverse. As the additives wear out the 0w50 will behave more like a 40wt or even a 30wt depending on the quality of the VIIs and the base stocks. I could be wrong but I don’t think the 0w oils on the market use much if any PPDs using instead PAO or Group III+ base stocks.

Here is a link from BITOG posted yesterday of a discussion of the blending of various oils from M1. Keep in mind these are suggestions from M1 and not intended to indicate their house formulas. http://www.bobistheoilguy.com/forums...2309835&page=1

None the less Flash's explanations have been the best translated I’ve come across.

One other thing I noticed after reading this entire discussion going back to 2003 or 2002 is the indication that PAOs were responsible for seal swell. This is incorrect as PAOs used to and some may still have the tendency to shrink seals whereas esters swell them. Hence the need to blend the 2 to balance the seal reaction out.

Flashwing

Nothing wrong with sparking a debate or a discussion. This topic is a tough one because it has been beat to death on this site and many others. You can find someone who has had a great experience with every single motor oil out there and then find a person who has had a terrible experience with the same.

I started looking into oil because I was tired of picking a brand and weight without really understand what I was buying. Understanding that is probably the biggest value you can get from reading up on it.

You guys will have to excuse me as a lot of this info is coming off the top of my head and some of it has fallen out since I had done a lot of research.

With respect to the VII's, my understanding is they work in both directions. VII's increase the flow capability of oil while cold while limiting the oil from thinning while warm. As the VII's are sheared the oil begins to return to the viscosity of the base stock.

You are correct regarding the 0w oils. My experience has been that all 0w oils are either Group IV PAO or Group V Ester base stocks. I tend to go with 0w because I know I'm getting synthetic where as due to the marketing laws Group III oils can be marketed as synthetic because of hydrocracking.

It used to be that oils such as 0w-50 were not able to be used because the index improvers would shear quickly and the oil would thin down under operational temperature.

Its hard to say what amount of shearing would take place in the rotary and the only real way to know is to have your oil tested. Other factors such as the amount of fuel in your oil can also cause the oil to thin.

Good catch guys. I'm a bit rusty on some of the info as it's been a while since I discussed oil on the forum. I had to make room in my brain for all the knowledge I need for Forza 3.