^ Good point which brings me back to my question. Shouldn't there be a way of draining the extra oil such as drain plugs on the oil coolers? Hello?!

 

That's my point exactly - it is Mazda's intention, by design, that their specified oil change amount is DIFFERENT than the total oil capacity for an RX-8.

You originally wrote and that is wrong - the owners manual for both cars do NOT read the same. On an 04 Miata, you should expect to drain nearly all the total capacity for an oil change. On an 04 RX-8, you should NOT expect to drain nearly all the total oil capacity for an oil change. They are different, BY MAZDA DESIGN.

The oil that isn't drained doesn't just sit there in some corner and stay dirty - it gets circulated and mixed with the new oil, starting immediately the first time you run the engine after an oil change. Further, colour of oil is absolutely NO indication of the protection being offered by that oil. Unless you're having oil analysis performed on samples of your oil at regular intervals, there is no way to observe how 'good' your oil is. Again, colour is NO indication, and that has been proven many times over. In fact, oil analysis results are indicating that oil with a couple of thousand miles on it protects BETTER than new oil, so black oil can actually be better than that golden clear stuff! Even further, Mazda's specified oil change intervals for the RX-8 are much shorter than oil change intervals for most European cars - even if you only change half the volume at each oil change, you're still changing it twice as often as on European cars like BMW, Audi, and Mercedes - so how is this a problem, when the % of oil changed vs. distance over the long term is the same?

Going back to the original postulation, with a twist:There's no difference - if you've followed the recommended oil change intervals, Mazda's assistance out-of-warranty for a sludged up engine would be the same whether the vehicle is a Miata or RX-8. Shocar implies that there would be a difference response, yet there is absolutely ZERO historical or factual basis for that assumption. Fearmongering, pure and simple.

Regards,
Gordon

 

That's Shocar's specialty, Gord.

 

How wonderfully optimistic.

The "design" allows for the engine to survive until the end of the warranty. After that, even a 50% faliure rate would be acceptable.

I still don't understand why this is an argument. Change your oil every 2000 miles. It wont hurt, it might help and it is cheap.

 

Okay, now I'm really curious. This sounds like Physics where you learn everything is backwards to the way you thought things were. What's the supporting data on this? I haven't taken the time to figure out what all acronyms in the oil posts mean and could use a little Oil Analysis 1A Thanks.

 

My only point is that maybe the engine oil should be changed more frequently than what is specified in the Owner's Manual. This would be for the good of the engine and the people who own these cars. The RX-7 Website seems to contain similar recommendations.

There is, in my opinion, more learning on other similar topics that RX-8 people will experience over time that will bring RX-8 maintenance more in line with what is commonly practiced with the RX-7.

For the record, I will change my engine oil between 2000 and 3000 miles. And yes, I know that the huge majority could care less about that.

Gord is correct, many on the BITOG site think that egine wear increases immediately after a fresh oil change. The wear then settles down. But I've asked about this over there (the partial oil change aspect). I did not get much of a response. I know some people will think that is because this is such a ridiculous topic. I would have expected some people over there to recommended the use of Lube Control as part of the oil change as a means of restoring some desired properties to the used portion of the remaining oil.

I don't think that a mix of old and new oil is any kind of planned optimization of the lubrication design done by Mazda. I know people will disagree with this.

Having two oil coolers for the high power engine is to enable more satisfactory performance
when using 5W20 oil. The lower power engine has one oil cooler for similar reasons. The European cars have one oil cooler for similar reasons, that being the recommended use of 5W30 oil.

But it appears that a cat fight of some sort is going on with with this topic. So it is ok with me if this topic gets closed or even deleted by the administrators.

 

I guess I'm flame-baiting here, but I happen to agree with you entirely.