Originally Posted By: 29662
The TCW-3 is ashless, and as such is much preferred for water cooled engines which operate at lower temperatures than those that are air cooled, which is primarily what the FC rating is for. Stick to the TCW-3 and you'll be just fine. If you use a FC rated oil in a water cooled engine you could see some deposit formations after some use. I speak from over 40 years of 2-cycle engine operation.
What would you recommend for a Rotax 518 water cooled engine used on an
Ultralight plane? If you have a brand name preference, I'd appreciate
that also.