Does anyone reccomend putting synthetic oil in my carburated 12a or is there a reason I've never heard of anyone doing that?

 

For racing purposes yes, if your street driving and easy on your motor, no. This is from Rob at Pineapple racing.

 

Well, let me clarify. It's perfectly fine for street driving (Rob and I have about 30 years combined running synthetics in street driven rotaries), but not if you drive like a timid housefraü. Mineral and synthetics both create carbon when they burn (and, yes, synthetics do burn just fine). Synthetics actually create less carbon...or at least what carbon is created does not build-up but, rather, tends to go out the tailpipe. But, you must drive it hard from time to time to ensure it blows out. You should be doing this already, because it is much the same for mineral oil.

From rebuilding engines run on synthetics, we notice less carbon build-up, less sludge in the pan, and less wear. That said, it's not necessarily wise to put synthetics in an old engine. You're closing the barn door after the cow has left...it won't undo wear; only prevent it. For the added cost, it's not going to do you much good.

Turbo rotaries also need to consider the issue of fuel blow-by, into the oil. Under boost, it is not uncommon for fuel to blow-by the oil control o-ring and contaminate the oil in the sump. This has little to do with the oil control o-rings being bad. It is normal. Fuel is a solvent, so it breaks down the oil, thus requiring frequent changes to prevent excessive wear. One of the big benefits of synthetics is the extended oil change interval, but if the oil is getting contaminated systematically, that advantage is nutralized; you still need to change the oil at the same intervals. Non-turbo rotaries, on the other hand, can probably stretch their oil changes to 6 months or even a year, provided they still change the filter every 3,000 miles. But, here, you still have to account for oil contamination by fuel due to either flooding or weak oil control o-rings. It normally should not happen, but over time it may get worse and worse. Yet another reason not to convert an older engine.

And, let me add, running synthetics may not even be economically viable in a fresh engine, unless you have a big investement in it. Mineral oil is very, very good stuff and comaritively cheap. Change it frequently and drive the car with spirit and you will be hard pressed to find a reason to switch to synthetics. Synthetics are not for everyone. You have to LOVE your engine.

If you do love your engine, we normally recommend Mobil 1 or Rotary Purple. Rob runs Mobil 1 and I've been using Royal Purple street and racing synthetics for many years (they sponsored a couple of my race car projects).

 

The main reason I was considering the switch to synthetics is to eliminate the white stuff on my dipstick and no I'm not trying to make an immature joke. I know you guys all know what I'm talking about. I get so much build up of that white slime that I can't even read the oil level which is a scary thing when you drive a rotary. Would synthetics even solve the problem of white sludge build-up? Furthermore, my rebuilt engine has 13,000 miles on it, am I at the point of no return where I should just stick with mineral oil?

 

What about this synthetic oil for rotaries only???

http://www.mazdatrix.com/q-supply.htm

 

Your problem is moisture. Either you have no venting for your sump or perhaps a cracked center plate. If you have no venting, just drill a small hole in your filler cap and see if that helps. Synthetic oil is good stuff but it won't cure an unrelated problem.

 

There's nothing wrong with it, but I can't see any advantages since synthetics that were not "designed for rotaries" work just as well and can be found at your local autoparts store.

 

Racing beat recomends synthetic, and I've allways ran it in my cars it's fine. Oh and I premix.

 

Mobile 1 user here. (Thanks to Rob) Well, except in my Rx-8. Thats using dyno oil until the the 4yr 50k mark is met. CJ

 

For Mazda's explanation of the milky substance on the dipstick:
http://www.finishlineperformance.com...09-05-1450.pdf

The article is talking about the RX-8 though. Been using Royal Purple in the RX-8 since its first oil change ~1500 miles.

Goodbye!
Edgardo

Wow that is some good/interesting information, thanks!

 

I've always ran Redline synthetic in my rotaries. It's good stuff plus if you do not premix it has a very low ash content and is just fine for oil injection still.

 

Redline is good stuff for the track but "racing" oils usually do not give you as much corrosion protection as those formulated for the street. Not a big deal if you get into your motor periodically, but most people would be better served with Mobil 1 or Royal Purple street formulations -- RP makes both kinds, but the racing ones use "Racing" in the name (e.g. "Racing 21").

 

I was wanting to know the answer to this same question. I have a 94 RX7 all stock with 82k on it. I drive the car fairly chill. I get on the turbos only every once and a while to make sure their still there. I have been using non synthetic. Should I switch? I read through all the answers only to get more confused.

 

If it were me, I wouldn't do it just because the motor is already well used. You can't undo the wear already done; you can't extend your oil change intervals (turbo engine have more fuel blow-by into the oil); and you aren't driving the car hard enough to justify a couple hp freed up by the synthetic oil. As I said, mineral oils are quite good and a fraction of the price of synthetics.

Think of your car as if it were a human and its age determined as if each "year" = 1K miles. (10K miles = 10 years old, 50K miles = 50 years old, etc). Then think of mineral oils as the "usual" diet and synthetics as a healthy, low-fat, high-fiber diet. The earlier you start the healthy diet, the more dramatic the long term effects. But, if you wait until you are 82 years old, it's kind of pointless. Can you do it? Sure. But in the case of engines, the synthetic costs 3x as much and the "end" is not so final...you can rebuild an engine.

Even on a younger engine, you should add up the additional cost of synthetics over the life of the engine. It could easily be $750-$1,000 above and beyond. Like I said, you have to LOVE your engine to invest in synthetics. For non-turbo guys, the economics are not so harsh because you can extend the intervals, but it's still not a slam-dunk decision.

 

cool thanks

 

I just like the extra little benifeit of protection. I mean i'm running 400+rwhp on a engine with 50k miles on it. As Rob says, I've pulled the pin. CJ

 

Racing oil? Redline has 2 different kinds of oils, "racing" oil and normal synthetic oil that can be used on the street. Is that what you're referring to? I used Redline "normal" synthetic 10w30. Never really heard that stuff called racing oil, only the straight 30 weight, 50 weight, etc oils they sell.

 

We have allways used the Amsoil in our rotary engine both for street and track use.. Also went 400+ on the MPV just fine!......................

 

what weight of synthetic do you recommend? 10/30 15/50 20/50???