Isn't the rotary a different beast, vis a vis oil weights? The oil is injected into the combustion chamber as well as the internal area where the rotor rotates against the eccentric shaft. So, it's like a two stroke in terms of its oiling with respect to the combustion chamber and seals, and like a conventional piston engine where the oil lubricates the toothed inner surface of the rotor and the eccentric shaft.

So, that being said, the lighter weight oil incorporates into the fuel mixture better than a heavier weight oil, right? And, isn't it easier to inject lighter weight oil thru injectors than a heavier weight oil? That's why we use 5W-20, right?

Now, another question, and I hope that dude with the animated unnecessary new thread/should have done a search blocking hand doesn't bust me, but, is the eccentric shaft/geared rotor section thing under pressure, or is it too just sprayed with oil?

Discuss...

 

5w20 improves gas mileage, so that's one reason we use it!

 

Actually, that's the only reason we use it - the extremely slight improvement in gas mileage. Everywhere else in the world (outside North America), Mazda specifies 5W30 for the RX-8.

Regards,
Gordon

 

maybe better related to other oil threads, but this one is fresh and easy to find--I had my fourth oil change (20k miles) recently, the earlier receipts always said 5w30 and I never really worried too much about it (there's a thread to the effect that although it says 5w30 they really put in the 5w20 per the manual but the computer doesn't allow entering that). Well at my last change I questioned the person doing the change and he said "yes it's 5w30, that's what the dealer recommends, it's $8-9 more for 5w20". I inquire about the free maintainence program and the extra charge. They said it's covered, and put in 5w20. The bottom line is I'm pissed. When is it ever OK for a dealer to use a non-oem specified grade oil???

 

I do not think the RENESIS is that different mechanically from prior rotaries. I have had four other rotaries before the 8, and always used 20-50 in Phoenix. Never had any engine problems. That is actually what the owner's manual specified for this weather. I cannot see where 5-30 or 10-30 would make that much difference.

 

Like Urchin said, Mazda recommends 20W-50 for my car. I suppose because rotaries thermodynamics aren't as good as pistons, and generate more heat. Why the Renesis uses such a thinner oil, I don't know. I suppose the engineers are the only people that know. Lets not speculate too much about it and just use what we're told.

 

Keep in mind the surprisingly small amount of oil we're talking about. Many drivers reporting consumption of significantly less than 1 quart per 1000 miles. So, we're not talking about a continuous "spray" , it's more like an occasional droplet that then gets spread against the rotor housing by the apex seals. There's no need for it to be "incorporated" into the a/f mixture, in fact I imagine that would dilute the oil and detract from its purpose of providing a compression seal.

 

I use 20-50 in my FD because the heat here in Miami is to much, and my oil pressure is to low at high RPM when I was using 10-30.