There is a current thread on the 1/2A forum about 1/2a fuels. Consensus is that for the ball/socket joint on Cox and the big end bearing on Norvell castor is a must. It seems quite logical though as ajcoholic points out, for low rpm use (1/2a Texaco, etc., synthetic should prove adequate, and I would think reduce varnishing. I also expect that using lower nitro % should give better "mileage". Kick the RPM up though and castor is cheap, reliable insurance.

jess.