Tim - the Bob that Tom Denney is referring to is Bob Kramer, DL USA. I think he is running synthetic at 60:1 or something like that, call or email him to find out.

My preference, and many agree, is to keep lubrication up on this engine. It's the "safe" approach to ensure long life as possible.

I will not go leaner than 45 : 1, and have been happiest at 40:1 after break in of 32:1. I use non-synthetic Pennzoil Air-Cooled.

THe oil wars will never end, and each brand and ratio has it's "champions" that recommend a particular setup. Without getting into the wars, the REAL issue is how accurately the carb is adjusted, and how well air flow is provided in the installation.

Regardless of oil brand or mix, what kills engines is poor airflow, overloading prop size, and overleaning of high speed needle.