Okay someone give me the long and the short of why our little rotary beasts don't like the synthetic stuff?? If someone has some reason for synthetic give me that too, just wondering, and my friend has a hard time believeing that we shouldn't be using it (he owns a supra, but he's not a dick like some owners). So enlightne me, him, and everyone else. Thanks.

Spyder420
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24.5k takes it, I just want my FD already

 

They LOVE synthetic. The turbos love it too.

BUT the oil metering system is dumping that synthetic into the chambers. No big testing has been done to see which synthetics for sure burn clean.

Get the oil metering pump adapter that lets you feed your oil metering pump 2 stroke oil from a seperate tank up front. Then you can run synthetic. It should love you for it!

 

IMO the only advantages to synthetic, over regular oil, is better cold flowability and better resistance to heat. Yes there is the longer service interval, but $5 a quart synthetic that lasts 3 times as long as $1 a quart regular doesn't add up. And that's if you have your OMP disconnected!

Cold flowability... Great for boingers that have complex lubrication systems with lots of tiny little galleries and a few dozen journal bearings and hydraulic lash adjusters that require good pressure right away. What do we have... four journal bearings and a dead-simple oil gallery. Beyond that, you really should be gentle on a rotary until the coolant and oil are at least halfway up to normal operating temperature. Synthetic was great on my old boinger-car, with a noticeable increase in oil pressure from cold startup, as well as increased cranking speed in subzero tempertures. (Unfortunately, I found out why not to switch a high miles engine over to synthetic oil... )

Heat resistance... C5 Corvettes specify Mobil 1 oil, and for good reason: They have no oil cooler (this may have changed recently though). Run one hard on the track and you will probably see the oil temp gauge PEG. Regular oil is only good to about 250-260degF and it would get ruined rather quickly under this kind of stress. Rotaries, on the other hand, will cook the engines before the oil can get that hot. Why bother with oil that can stand 300+deg temps when the engine can't even stand 250?

 

Royal Purple 20w-50 or 10w-30?

 

I had posted this in the 3rd Gen forum, but here is the same info straight from the Racing Beat Rotary Performance Technical Manual:

"The Mazda factory does not recommend the use of synthetic oils in their rotary engines - specifically addressing this issue in the Owner's Manual.

In 1979, Racing Beat began testing synthetic lubrication products. Without a doubt, the best synthetic oils do perform well in extreme heat (over 300 F) and extreme cold (below 32 F), but by the nature of Mazda's rotary engine, the oil temperature never exceeds 250 F without severe engine damage due to other factors. In Souther California, we have difficulty seeing the low-temperature benefits: however, when we put synthetic lubricants in the engine, transmission, and differential in our IMSA GTU race car, we immediately saw what we later found to be a common result: The oil temperature in all three locations dropped 5 to 10 F for the same operating conditions. This is apparently due to two factors: reduced friction between sliding surfaces, and reduced foaming. As we continued to use synthetic oil products it became clear that they genuinely reduced wear. We also found benefits in street use. On two occassions, cars with "scratchy" transmissions synchronizers were completely cured by a change to synthetic gear lube. After many years of experience with these products we have observed only one problem: because of the reduced friction, the time necessary to break in an engine, transmission, or limted slip differential (standard differentials are no problem) is excessively long, so we recommend using mineral oil in all three for a time to ensure rapid break in."


Hope it helps...