Lynn,

       I presume from your comments below that the use of a synthetic in the sump

to be injected is not a good idea........What is your opinion on the use of synthetic

2 cycle oil as a premix for our a/c use other than the fact it is more expensive ??

I have no experience outside of synthetics since the 80s. I never had an apex seal failure.

But, I never built an engine with the metal apex seals. The early apex seals were all one piece carbon 9MM seals. When Mazda went to 2 piece 3MM metal seals we machined down stock carbon seals and raced on them. Everyone said that the metal seals would groove the rotor housings if raced, so I just did what other people were doing at the time.

 

Modern Mazda 2 piece 3MM seals are raced every day and do not damage the rotor housings at all. You can do it by over reving the engine, and the chrome will wear out at 150 thousand miles, but you have to work at it. So that problem should not be a factor. And that is running sump oil through the apex seals. Plus the modern seals are a far better product than the first sets produced by Mazda.

 

Now we run the Mazda racing carbon 3MM one piece seals, and I have a set of Mazda ceramic seals that I will use some day. They will take anything you can do to them.

 

The metal seals are fine with sump oil, and should be fine with any modern 2 cycle oil. The RedLine synthetic 2 cycle oil is the very best you can use, but the housings are going to outlast your interest in aviation, so the expense is not justified. Any 2 cycle oil should do just fine. The feature most important is does it burn clean, and lubrication is second.

 

At aviation RPM there is no stress on the engine. Mine idle at 2,200 RPM. The bearings are over twice as big as they need to be. The max HP is produced above 10,000 RPM, and there is a bunch of stress on the bearings at those speeds. Typical oil pressures of 115 pounds are used up there. The rotor sides are shaved down because the crank flexes into an "S" shape and the rotor tips drag on the irons. Imagine that crank bending at all.

 

Some people have raced a weekend and forgot to mix in the oil. No detectable damage.

So I never let the car race with out me being there.

I just talked a guy in Florida,through care and feeding of an engine I built two years ago and have not seen since.

 

But I run on as usual.

 

Lynn E. Hanover