mrtux

Basically i got the new rx8, and after i drive it around and park it, it seems a little warm/hot is it usual when u are breakin it in? or is it my driving? am i too hard on the engine?

rx8daniel

Rotary engines run hot. Hence two oil coolers and 7.1 quart capacity on the high output engine / 1 oil cooler on the low output.

mrtux

so it's typical for it to run hot? during the break in period is there anyway maybe to play it safe like after u stop run the motor a little bit and shut it off?

khoney

Are you sure about 7.1qt? My owner's manual (6spd GT) says 3.6 or 3.7 (I forget which, and am too lazy to go outside and look) including the oil filter. Also, someone posted about overfilling their car using more than 4 qts.

KyngNothing

There are 7.1 quarts in the car, 3.6 are changed at each oil change (the coolers etc do not drain completely)

Mitch Strickler

As I recall the specs, the automatic has less oil, 6.4, but also has two oil coolers. The idea that only about half the oil is changed each time is a very big departure from normal engine practice. It would raise questions about keeping the oil clean. Has that been the same for previous rotaries? How come I never saw any comments in reviews, Mazda's tech writeups, etc?

syntrix

Or...

How easy is it to pull the oil coolers and manually drain them at each interval?

Or would that be bad as the engine might not preoil on startup properly?

mikeb

that would not be easy

CERAMICSEAL

The 3rd gen rx-7s had 2 coolers on their R package cars. 2 also on the automatics but the one on the rightside is a trans oil cooler. All 8s have dual coolers but again the auto only uses 1 for the motor. I think the auto has a capacity of 6.1us quarts.
Since less of the total is being drained its defintely a good argument for a more frquent oil change. I personally like 2500miles.

mikeb

too bad mazda will only do free oil change every 5k

OverLOAD

They'll do an oil change whenever you want... just pick your maintenance schedule. Sched A for every 3000 or B for every 5000. I'm going to go with Schedule A, so that they give me the goods early, and I can do it myself after that...

mikeb

thanks
I didn't know that

Mitch Strickler

Mine says the schedules for U.S. (except Puerto Rico) cars are either 4 mo/5,000 miles or 6 mo/7,500 miles, for oil changes. I have asked the Mazda people at their national number if my free maintenance can be on the 4/5,000 schedule, and they said yes.
I would also like a better explanation of oil capacity than I have seen in my owner's manual or this thread. The manual simply gives low figures (3.7 quarts) and ignores the engine oil cooler(s) -- one for auto, two for manual. People posting on the thread say there is more oil in the coolers, but it is not exchanged when you change the oil. What does this mean? How is the oil lubricating the engine cooled if it is separate from the oil in the cooler(s)? If they are not separate, why doesn't all the oil get changed? Obviously, I'm missing something here, but nobody has explained in terms that my non-mechanical, but logical, mind can follow.
I have thought of one logical -- and probably off the wall -- solution. The fluid in a closed oil cooler system may be routed near hot oil in the closed engine oil system, picking up heat. It then is cooled by air at the oil cooler intake, similarly to the car's radiator cooling water/antifreeze, or the a/c radiator cooling a/c fluid. When the oil cooler fluid returns (is pumped?) back next to the hot oil, it again picks up heat, completing the cycle. The fluid wouldn't have to be oil, and engine oil would not be dirtied no matter how many miles between oil cooler fluid drainings.
Mitch

CERAMICSEAL

Oil is pumped fom the front of the motor to the cooler/s and then to the back of the motor where it is filtered and sent through various galleys and eccentric shaft (which cools rotors and provides bearing protection)
When you change oil most of what is in the engine drains out. The coolers mostly retain their contents until the next startup.

Mitch Strickler

Thanks, Ceramicseal.
You say that one of the functions of the oil is to cool the housings. Isn't there another cooling system in the RX8, which uses antifreeze and the main radiator, to do that? Maybe you are referring to backup cooling by oil. My Acura GS-R had that, with some oil sprayed on the piston. I can understand your explanation of a design in which most of the oil that is in the coolers does not drain out when the oil is changed. What I don't understand is why it would be designed that way. Surely it is not beyond the capacity of engineers to get most of the oil out of the coolers, either through separate drains or other methods.
Why would Mazda choose to leave dirty oil that would start circulating through the engine almost as soon as it starts up after the oil change, diluting the clean refill? And if that is what happens, why would Mazda not say a peep about it (or any of the experts who wrote up the car)? Isn't this something new, which would have attracted attention?
I have more questions, but I'll wait until those are answered.
Mitch

IWANTMYRX8

Antifreeze/Coolant flows through the engine block, or I guess in this case the cooling slots throughout the houseing. It will help disapate heat from the block as it flows though and recirculates back to the radiator to be re-cooled.
Oil actually makes contacts w/all of the moving parts, unlike coolant. In addition to lubricating the moving parts and reducing friction, it helps to cool these areas as it takes a portion of the heat away from theses parts as it is created.

(someone please correct me if wrong, but I think that's your answer)

syntrix

What a lot of people don't understand is that oil will usually last MUCH longer than what the manufacturer recommends.

Anyone ever do an oil analysis after a few oil changes on a new rotary engine?

I'm sure that in most cases, the oil that looks black will not have broken down as much as you think.

Either way, I'd still rather change it all out, but I'm sure that it's going to be just fine.