Rotary Engine Run In!

[NoDOHC]

Originally Posted by RETed

There is so much fuel in the engine that it bypasses the metal oil control rings and the oil control o-rings.
Remember, Mazda designed the oil control ring system to keep oil out of the combustion chamber.
Oil is significantly more viscous than fuel.

I have a feeling the oil control rings are just "hydroplaning" over the gobs of fuel inside the engine in a disgustingly overly rich condition, which allows the fuel to eventually enter the oil supply.

I've drained oil pans where the "oil" flowed as thinly as water...
You can smell the gasoline mixed in with the oil too.

That is a new one to me. I have never seen any oil dilution or oil contamination in any way in a rotary engine. I have 1,000 miles on the oil in my engine right now and it is still clear and clean looking. Initially I concluded that this was because combustion by-products could not get past the side seals to get to the crankcase.

Then I saw a rotary that pressurized the crankcase when revved, it turned out to have a worn out spring under the inner oil control ring (the ring had been spinning relative to the spring - the spring tab apparently was not installed correctly). This disproved my theory about the combustion by-products leaking past the side seals, as only combustion by-products or pre-combustion compressed air (coming from same chamber) could pressurize the crankcase.

These findings would tend to reinforce that oil dilution is possible, only I haven't seen it. What conditions will cause oil dilution? Does it have to be rich-misfiring?

I never let an engine run rich of 13:1 (in vacuum), as this will wash the oil film off the seals and decrease compression, accelerate wear and waste fuel for no reason. On a piston engine sometimes you have to run rich to protect valvetrain, but the rotary is immune to burned exhaust valves (although not exhaust sleeve failure).