i have to say this is interesting......i have about 42200 miles on the car, changed the oil every 3k miles, runs just like the day i bought her, even better i have to say, i dont c the need to switch to 5w30, 5w20 castrol has bein the doin the job fine for the past 42k miles.......i live in texas, n it gets hot down here..

 

There seems to be no evidence taht 5w20 oil is damaging the engines in NA. It's all "internet information/rumors" at this point.

 

Put it this way, while under warranty, might as well stick to the specifications. If it goes kaboom! at least Mazda can't fault you for not using 5w20.

 

but its also true that only N/A market Rx8 get the newest recall.

 

Still can't say that the oil is causing it...

 

I wouldn't use a non-synthetic oil that had a wide "spread" of SAE viscosities (Castrol Syntec 5w40 for instance) - the formula uses long chain polymers to achieve the goal, but they don't hold up in the long run.

In fact I wouldn't use any Castrol product (aside from the fact I make oil, and they are the competition) they have a history of deceptive advertising, and have recently failed to live up to minimum specs and been dropped as a recommended supplier, by GM.

story here

(Not meeting GM's minimum specs - think about that for a moment....)

S

 

So here is an oversimplified synopsis, correct (or flame) where I am wrong on the issue of motor oil.

1. Mazda through their owner's manual recommend non synthetic engine oil, weight 5W20 inthe U.S. 5W30 in the rest of the world.

2. The 2004 RX-8 in some locales had problems with engine failure which has been blamed on failure of the apex seal in the rotary engine. According to the majority of posts, this appears to have been largely limited to the southwestern United States in extremely hot, extremely dry climates.

3. Mazda has never come out with a conclusive report on the cause of these engine failures.

4. Many forum members have had perfectly good luck running synthetic opils such as royal purple 10W30 pure synthetic oil in their cars for tens of thousands of miles. (Anyone crossed 100K on synthetic?)

5. There is no concensus on what is actually best to run in your car because most studies that have been done have not been scientifically proven to represent actual conditions inside the Renesis engine.

Have I missed any major points? Basically, the two major arguements that I have read about 400 times this month revolve around, the utilizations of Dino versus synthetic because of fear of engine sludge and carbon build up, and the use of 5W20 versus 5W30 due to start up lubrication and heat transfer to the coolers.


Sooooo, until we see something official from Mazda or a truly scientific study on the Renesis engine, people under warranty worried about the dealership or mazda trying to void their warranty for using synthetic oils as it is expressly mentioned in the manual will for the most part stick with dino, and those who have seen the effects of synthetic oils in piston (and rotary engines) will continue to use and promote synthetic oils.

Sounds like things are essentially down to a Ford/Chevy arguement to me....

What did I miss?

 

I just can't believe I spent another half hour of my life reading another freakin thread about oil! Argh! Only good thing is that in two more posts, I'll finally reach a meager 500 posts!

 

Walmart Supertech meets it (5W-30 though)

 

I saw a couple references to the GM6094M specification as it relates to Castrol 10W-40, which is not the oil suggested for use in the 8 anyway. There was no mention of their 5W-20. For that matter, any idea why the 10W-40 doesn't meet GM's spec? Is it anything we would even care about?

At Castrol's site, they claim that their 10W-30 meets the GM spec, but there's no mention of it on the other grades.

(Data point here -- 40,000+ miles on Castrol GTX 5W-20.)

 

I use oil X. Anyone who doesn't use oil X is a heathen.

I think that pretty well sums it up.

 

Only Castrol products Syntec and Syntec Blend 5W-30 and 10W-30 meet the GM spec. Have no idea as to what the significance of that is. No Motorcraft (Ford) oil meets it (unsurprizingly).

 

This is worst than a pepsi\coca cola debate. And after all the shared comments and thoughts .......... still it seems to be a big question mark as to what works best. And to make matters more shaky ...... mazda doesn't seem to want to include any thing other than dino 5w20\5w30 in their recommendations. Even though there is documented proof from owners, that synthetic has been used with much success.

I'm about 2 days to 1 week from getting my 8 {Depending on how much more I can work the dealer} And concluding from all I've read, it seems safe to assume that a 50\50 mixture of 5w20 & 5w30 would be the way to go.

Weather it's dino or a synthetic blend is still up in the air. So, if anyone has any recommendations on a good synthetic blend that I can buy in bulk, please chime in.

In the meantime ........... I'll continue my research on the RX8.

Regards

 

GTX 10W-30 meets it as well: Castrol GTX Grades

But like you said, if that's significant to us -- dunno.

 

If it's 5W-20 only in N. America, is the ECU/engine programmed differently—for 5W-20 instead of 5W-30—in N. American cars? (That would be reason enough for me to stay with 5W-20.)

 

I would think it would be just slightly, but don't really know.
Think that was part of the reflash on the 4206 recall. (I think that was the number!)

 

1. I dont see it in my manual? Not to mention, Mazda does not recommend the use of Aftermarket parts. who actually listen to that ? including those who said Mazda does not recommend the use of synthetic oil.

Seriously if Mazda's manual means Bible to you, then you should use nothing but Mazda parts, nothing but Mazda's Oil.

2. if your point 3 is true, how the hell would you know the Apex seal is the cause of failure? as far as I know all Mazda dealerships are NOT allowed to open any of the problem engine, they take it out, put the replacement in, and ship the old one back. Anyone ????

3. See 2.

4. You'll see it in the near future, some have 60 K already. I have 31K in my 2 years of ownership.

5. Thats true, but does that mean Synthetic is not good ?

They cant void Warranty because someone use Synthetic oil. at least in the US market. People can use whatever they want. but why bash synthetics ?

They did messed up the programming in pre-recall flash. Now it should be fine. after all these time I think damages already been done (alot to, especially 04s), I have 31 K of Synthetic miles and I think the first 8 K were 5w20. I dont worry about it much.

 

I do have some (old) data for the synth/dino discussion - I was one of the very first people to destroy a rotary with synthetic oil.......

1975. I had read in Popular Mechanics about a new generation of oils based on synthetics ".....as used in the space program!!"

Drove 800 miles to the nearest Mobil1 dealer and got 5 cans (at six 1975 dollars per!) and did an oil change.

Within 30 days, the coolant seal 'O' rings had turned to liquid, and the car was drinking it's anti-freeze at an alarming rate. Took a while to jump thru all the hoops but Mazda put a new motor in for me.

I'm not sure when the manuals finally came to state "no synthetics" but that is the problem they were addressing, housing-to-plate 'O' ring destruction.

People who looked at the "no synthetics" warning just assumed it was "the oil burns too slow/the oil burns too fast/the oil destroys apex seals" etc. Theories purely based on fantasy.

It never was an apex seal issue.

Since then, Mobil1 formula has been reformulated (many times) and the 'O' rings have long since been upgraded to Buna/Viton etc.

The problem has been long solved, but the synthetic warning persists, for reasons that only Mazda Japan knows. (Once bitten....?)

S

 

Its always easier to say no then carry liability.

Since so many people still living the the past, Mazda probably like hey, why not use the opportunity ?

the picture from Mazda is another bullshit, people need to drive rotary hard to get rid of carbon, if they granny it, no matter what oil u use exhaust port still gonna be clog with crap. but at least by doing so they can blame the customers so they can deny warranty claims !

 

The logic behind "Mazda says no synthetics just to protect their butts" has always escaped me.

If it's true that synthetics are better for the Renesis engine, and if it's true that synthetics lead to longer Renesis engine life, and if it's true that synthetics mean less, rather than more, engine problems—then economically is it not in Mazda's best interest to encourage the use of synthetics, if not, at the very least, allow them? I just don't see what Mazda gains by promoting the use of an oil that's less good for their engine.

 

Re: nycgps ~

Thanks for the tone, anyhow, perhaps this is a new change to the manual, I haven't read them all from year to year, and invited corrections where appropriate. In the 2007 Mazda RX-8 Owner's Manual, Maintenance and Care, section 8-12 Engine Oil

"!Caution
Do Not use either synthetic or semi-synthetic motor oil. Otherwise engine starting performance could worsen."

That doesn't tell me "We don't recommend" it says "Do Not" subtle difference I know, but subtle technicalities are the name of the game sometimes.

Why they offer this caution I don't know, and I'm not preaching against the use of Synthetics. Maybe they say it because they fear what some sketchy oil manufacturer in china may formulate into their low end synthetic cheapo oil (Melamine contaminated food) that might start eating "O" rings again, so easier to just issue a blanket statement than dealing with the reporcussions? Who knows..

As my job entails contract interpretation, I know how companies operate and would not put it past one to try to weasel out on a technicality like this though, so while I am still under warranty I am going to play it safe and follow the manufacturers recommendations.

So far as this goes, "Seriously if Mazda's manual means Bible to you, then you should use nothing but Mazda parts, nothing but Mazda's Oil." thanks again for the 'tude, I generally do abide by the manufacturer's recommendations where reasonable during the warranty period on any new vehicle I buy, if I can get a quality replacement part that is no threat to my warranty (See recommendation versus demand) for a lesser price I'm not stupid, if that makes me a chump or somehow worthy of mocking, so be it.

 

I'm looking at the Mazda North America Warranty Extension.
2004-2006 RX8 powertrain warranty to 5 years/60,000 miles.
Correct Me if I'm wrong, but the warranty was increased, not lowered.

 

I think its cheaper to replace a few engines than multi-million dollar lawsuit.

Especially in America, a place where people can sue for McDonald's hot coffee being too *hot*.

the *Synthetic is bad for rotary* has buried very deep inside alot of people's mind, if Im Mazda I think I will take advantage of it too. at least Im sure I can deny lots of warranty Claims + safe from being sued.

Im sure Mazda knows that u gotta drive rotary hard to get rid of the carbon, I think even the old KKM engine got some carbon issues. but there is no way that Mazda can issue a statement like *Please drive your car hard to avoid problems*

People can use whatever they want, but no hating synthetic please

this is going off topic guys, its time to stop this, I think 5w20 is not so good for rotary (any engines, actually)

 

...maybe Motorcraft oil does not meet GM spec because Motorcraft oil is made for Ford and not GM??......So they don't have to meet GM spec. That doesn't mean that motorcraft oil is junk, does it?