Chris, I have been using Synthoil brand synthetic oil in my 90 Carat for
about 115k miles (145k total) and have had no problems to date. Now I'm
going to switch to Castrol Syntec 5-50 wt because Synthoil is $10 a quart
and has to mail ordered. The cost is actually not much higher than
regular oil because you only change oil every 50k miles, change filter
every 3 to 5 thousand miles and top off. So it works out to about $15
every 5 thousand miles. Castrol had some info on synthetic oil @
www.castrol.com

Steve and Jo Ann Wacker
San Marcos, Ca.
90 Carat
86 Syncro