What you just said only applies to non-synthetic oils
That is interesting, I wonder how my used engine burner works because it do not use synthetic oils in it.
All, oils burn. Linseed, Coconut, Mineral, synthetic, Hemp seed, peanut etc If you want to talk about deposits in the engine, look at the ash content. That is what leaves deposits. Look on the specs of the oil can if you can find them.
Seizes have nothing to do with fuel mixture. You can run a 2 stoke all day at very lean conditions, just don't open the throttle over say 25%. When you have low RPM and low power, auto lubes can be as low as 200:1. Sure mixtures are related but get the facts right before you diagnose a problem.
If it is pre mix, lean mixtures means you have LESS oil. That is coupled with less cooling from the incoming mixture which means the engine is not cooled correctly, WHICH means the little oil you have overheats and breaks down and cant do its job.
If auto lube, then its just the engine not getting the cooling effect from the fuel vaporizing which still then leads to oil breakdown and seize.
Start diagnosing seizes with oil failure and go from there.
I can press in a big end pin in a crank with 5 tons. It doesn't seize. Wash them bone dry and try that again. You have a much higher chance, I'm not talking about wiping it with you finger, there is enough oil on you finger to stop it seizing.