30 wt Oil
I definitely agree it is an exact science! I was NOT recomending that he uses 30 wt. Maybe Stihl went TOO light. The SAAB manual transmissions in the late 70's and early 80's use 10W30 oil to lubricate the transmission AND THE differential gears, (all in one, frontwheel drive) You would never get it to shift WITH 90 WT, in the coldest days of winter if it didn't warm up for 1/2 an hour. but if you didn't change the (10W30) it EVERY 20,000 kilometers or sooner, you were probably headed for trani failure, as so many tranis did on those cars (900 series) I have since switched to REDLINE MTL synthetic, and have about 360,000 km. Take care Mike.