See my above post!

 

Good point, and this seems to be why bearing failures are uncommon.

 

Excluding fuel dilution, what do you suppose leads the rotary engine to thin oil more aggressively than a piston engine?

 

This is an extreme circumstance.... IIRC, the oil in that engine hadn't been changed for over 10k miles.

Also, one other way that rotaries are harder on oil than piston engines---- the stationary gears and corresponding rotor gears, and the shearing of the oil associated with this.

I've posted it before, but I'm a big fan of Idemitu oil..... 20w50 in summer months and for tracking, and 10w30 in winter months. I can't see any good reason to go with a straight 50 weight, unless you like pumping molasses through your engine at cold start.

Edit: one more thing..... on our fresh builds, we don't see excessive fuel dilution. This is based on observing the consistency, color, and smell of the 500 mile and 1500 mile oil changes when customers come back during breakin. A lot comes down to using all new oem internal seals/springs, and clearancing them correctly.

 

The reason is because SAE 50 quickly thins out to the equivalent viscosity of 10w-40 or even 10w-30 when exposed to the high fuel load of an FD. I've been running SAE 60 all winter with no ostensible ill effects. My oil pressure is a bit high at start up, but I drive the car easy when its cold anyway. Like I said previously, I think all the cold start wear is more marketing hype for additive manufacturers (where are those guys now?). I saw a dramatic reduction in wear metals with SAE 50 on my last 2k OCI, and plan to keep using it.

Can you obtain a couple of samples and send them in, Rich? If true, this is strong evidence that your builds are "superior". If anything, I would expect fuel to be higher during break-in, and that proper sealing would occur later.