I have run a lot of 46LA's. I also work on them. DOWNUNDER is correct. You need mostly castor oil to get good life out of these engines. I have found that SIG 5%NITRO-20%CASTOR with 4 ounces of KLOTZ added per gallon makes a good fuel. This gives 23% total oil. The KLOTZ seems to keep the engine cleaner inside. Never run the engine too lean. Always back it off rich a few hundred RPM. I think that the engines with peeled nickle liners are usually abused by being set too lean without enough oil. This is my two-bits worth.

Regards, Duane