RX8 rotary engine failure


#1

I recently purchased a 2008 rotary engine Mazda RX8. Now I’m reading all over the Internet that the only reason Mazda North America requires the use of 5W-20 weight motor oil is to meet Federal fuel mileage standards, and that the oil is too think to adequately protect the engine, resulting in early engine failure at 30,000+ miles. I have confirmed that in the rest of the world Mazda recommends 5W-30 weight oil, and have read documented cases from Australia of rotary engines lasting 200,000+ miles. Does anyone know if it is alright to use 5W-30 weight oil in the RX8, or would it void my warranty?


#2

How long is the powertrain warranty on that car? If it is the typical 5 years/60k (or more) coverage, then at least you don’t have to worry about engine failure until the expiration of that coverage.

Unless you can confirm from a reliable source (note: Internet sources of information are not necessarily authoritative or unbiased) that there are indeed many early engine failures in the US that can be attributed to 5W-20 oil, I would suggest that you stick to what is specified in the Owner’s Manual.


#3

You conclude that 5W-20 is thicker than 5W-30 (the word you use is “think”). 5W-20 and 5W-30 oils do have a difference but not one so great that engine failure at 30,000 would be the result. The 5W-30 may be the oil that is “to think” to protect the engine.

Use what Mazda requires.

On the practical side why would you admit to Mazda that you used a oil they don’t recommend? how would they know unless you told them? maybe you are just the “tell all” type.


#4

Apologies; typo. “Think” should actually be “thin”; the articles I read suggest the 5W-20 weight oil is too thin to protect the rotary engine, citing Castrol as stating on their bottles that their version of 5W-20 should only be used in vehicles that make short trips.


#5

The Mazda rotary engine has a well-deserved reputation for long life, often lasting 300K miles with normal maintenance (200K is nothing, really, to these engines). I’ve never heard this story about RX-8 engines lasting only 30K.

The twin-turbo 13B engine in the gen-3 RX-7 has sort of a “hand grenade” reputation, but not the normally aspirated engines.

Changing oil at the recommended interval is the key to long life with a rotary, and you can NEVER let one overheat. Other than that, drive it as hard as you like.

I suggest you use the oil specified in the owner’s manual. Read it carefully, it may allow more than one multi-grade oil.


#6

I would highly advise you to use specified oil and check it often. The rotary engines have a habit of burning it at a higher rate than piston based engines.

Mazda even extended the warranty on all RX-8’s to cover the components—>

http://www.google.com/search?hl=en&sa=X&oi=spell&resnum=0&ct=result&cd=1&q=mazda+rx8+extended+warranty&spell=1


#7

i’ve read that Rotary engines require regular(non-synthetic)oil of a specific formulation.if i were you,i’d use exactly what the owners manual suggests.i think it has something to do with the fragility of the engines sealing surfaces-the oil needs to have a certain mix of lubricants,additives in it to keep the engine happy.vw vortex has a very good technical section on motor oil(you don’t need to be a member to view it)i believe that is where i read about it.


#8

“citing Castrol as stating on their bottles that their version of 5W-20 should only be used in vehicles that make short trips”

Have you seen that wording on a Castrol container? I know that I haven’t!

Right now, I would put those articles (internet based, I assume) into the same category as those junk e-mails that claim the CEO of Procter & Gamble stated in an on-air interview that “all of our profits go to the The Church of Satan”.

Anyone with a functioning brain realizes that the CEO of P&G never made any statement of this sort, and with that as an example of the type of tripe that is bandied about on the internet, I would suggest that you go to a store, and look at some Castrol bottles for yourself, rather than accepting that information at face value.


#9
I put a lot of miles on my RX7 and I used the recommended oil and weight.  As I recall it was 10W30 then.  Those engines are great.  Mazda knows what they are doing.  200,000 miles is not old for a modern rotary engine that had the Mazda recommended maintenance performed.

#10

I have an RX-8 . . Mazda just extended the engine warranty to 100,000 miles. Rocketman


#11

Mazda sent owners (well, I got it, anyway) . . . an extension to their original warranty and a video which addresses a few problem areas . . . one is type and weight of oil to use . . . they said to use regular (dino) 5W20 and to check the level every other fuel fill-up. Rocketman