Here's some pictures of a 12A engine that has been treated with synthetic. For all those who argue that synthetic burns better than regular oil take a close look at these pics. I have worked with other engines that have been treated with regular oil and look a lot better than this one.

 

I think there's more to the story than that. How many miles on the motor? How frequent were the oil changes? How often was the motor revved to redline?

I don't buy it. I've torn down a motor that looked similar that used regular oil. It had been kept at low rpms for years, and failed due to carbon.

I wouldnt jump to any conclusions based on one engine.....there is absolutely nothing wrong with running synthetic in a rotary, period.

 

Break out the oven cleaner...

 

Housings look good from what I can see.

Royal Purple user here. I hear a lot of he say she say on running synthetic through the OMP. Mazda did not recommend it because synthetics were crappy burning, but this was 10+ years ago, technology has improved vastly. I couldn't care either way if it was good or not to burn, I premix

 

I purchased this car from a lady that owns a large car dealership in Oregon. It was well taken care of. Oil change every 3000 mi. and car had 99,600 mi on it. Here's pics of the car. It's an 81 and in excellant condition. 9 out of 10

 

Prolly never saw redline. You have to WIND IT OUT once in a while. Even piston engines get carbon buildup bad if you don't get on them at least once in a while.

I thought it was funny, my old co-worker had an '80s Firebird he bought new, and took EXTREME care of it. It was always shiny clean. He said he never drove it above 55mph. He wanted to keep it pristine (why?).

Anyway, his engine started having detonation problems because it was so carboned up. His mechanic told him he has to get on it once in a while.

 

from what i can tell the car was running rich(carbon build up) ,run hot a couple of times(cooked oilsyndrome),leaked antifreeze into the engine(white haze on rotor, and had an oil leak !!
Ive used synthetic oil for about 4 years in mine ,9k all the time
no problems as of yet

 

nice looking car . I'll bet it was never rev'ed past 4000 rpms.

 

Mazda knows that this is a problem, back in the day they made a special tool to unlock the engines if they got carbon locked and even today the make an engine cleaning kit for the Rx8 to de-carbonize the engines. I bet that even this engine was salvageable before breakdown with a little bit of work. I have seen it way to many times when people have brought me Rx7s or sold me Rx7s with "bad motors." First things first if I can get them running I nail them with some engine cleaner a foaming decarbonizer right down the carb while running then take them out and run the dog **** out of them all through the high rpm range, you would be surprized at the number of bad engines that turn out good with 25$ of supplies and 2 shop hours

 

you wanna know what is bad about using synthetic oil in our cars.... its called $$$$

 

It probably wasn't..until I got it. I got it from an older woman. I'm only the 2nd owner.

 

While the build up does look a little different than I've seen, it's not even close to the amount of carbon I've seen in most engines I've torn down. When Mazda issued it's anti-synthetic decree many years ago, some synthetics worked, other didn't. They took the position no synthetics ever as opposed to recommending the ones that did work. Synthetics have changed a great deal since then with much better formulations. Royal Purple is one synthetic that has been used with grat success.

 

I was using Mobile 1 synthetic. Don't know what kind what kind the previous owner used. I just know it was synthetic.

 

35,000 miles in 6 months on my 12a that had 124K with dino oil prior, zero issues.

 

what weight on syn oil do most people use, because on reg motor oil I use higher weight 20w50. I would like to try out syn on my next oil change thinking royal purple

 

15W40 is regularly available, I would imagine most people run that or thicker.

 

This is coming from another engine builder.. I was told that a layer of film probably from the burning of synthetic oil developed over the entire combustion chamber and components. So perhaps different synthetics burn differently.

I just stick with regular dino oil since I never had any problems since my car was made. Plus as mentioned above... $$$

Premix for me too! 1/2oz TC-W3 two stroke oil per gallon of 87 octane chevron with techron gasoline

 

ive torn down a zillion engines, and seen ones that looked WAYYYYY worse than that, that im sure were using dino oil.

Synthetic doesnt create the problems you are seeing.

 

the issues associated with the tear down that is shown in the original post look more like the motor was severely overheated. Look at the discoleration on the rotor. It's definately a severe overheating issue. This problem has nothing to do with synthetic oil.

 

Mobile1 isn't even a true synthetic anymore. It is based on the same stock as other dino oils.

 

YEARS ago mazdatrix disassembeled a motor that was run only on mobil1 and said it looked great inside.

i've owned motors that were run predominantly on synthetic and they had carbon buildup too. don't expect it to be crystal clear in there. it's still burnt oil and over 1700*F in there.

 

what about if you polish the rotors to a mirror like finish?q

 

Then you'll have very shiny rotors.

 

Started on Royal Purple at oh...107k? I am fine, as far as I know.