Originally Posted by
bigedmustafa
Keep in mind that bushed engines such as the O.S. LA-series and the Thunder Tiger GP-series engines require a significant amount of castor oil as part of the lubrication content of the fuel. The ideal fuel for an O.S. Max .65 LA would be 10% Nitro and 20% to 25% oil content that is 100% castor oil. The castor oil actually helps "float" some of the engine components at speed to prevent excessive wear.
These engines offer adequate power for their size, they can be very reliable and very long lasting. Running these engines with 100% synthetic lubrication or 80/20 synth/castor fuel will chew them to pieces.
I believe the primary reason that bushing engines have fallen so far out of favor in recent years is that the fuel commonly available at most hobby stores simply isn't designed for these engines and getting good running results is almost impossible for novice pilots who aren't familiar with the fuel requirements for these engines.
It's weird seeing my comments and opinions from six and a half years ago!
I'm happy to say that I still believe my old opinion was correct. My fuel recommendations weren't solely for the .65 LA, but I was thinking of the Thunder Tiger GP and K&B Sportster series engines as well.
The O.S. .65 LA is a terrific bargain among .60-size two stroke engines, and time hasn't changed that. They are powerful, reliable, and easy to tune; I wouldn't hesitate to recommend the .65 LA for most applications.
To clarify my comments about the .65 LA in particular, I believe that it would be adequately lubricated by fuel with an 80/20 synth/castor oil package. I wouldn't run a K&B Sportster with the same lubrication, however. I'm still confident that a 50/50 synth/castor blend would be better for the .65 LA, and would result in a longer lasting engine and better performance over the years.
O.S. Max LA-series engines that are noisy, down on power, or finicky to tune are usually the ones that have been run for a while with synthetic lubrication and they've simply worn down before their time.
The bottom line? The .65 LA is a very good engine, just don't run it with fuel made with 100% synthetic oil.