Has anybody used a quality 4 stroke motorcylce oil?  They tend to provide
good gear life performance as the transmission is often the sump.  They also
resist foaming at very high RPM. -- Ian

Ian,

 When I worked for Kawasaki they tested tons of oils, a few stood out. I don't even know if it is still available, but Keystone 20-50 petroleum based was what they used on the wholesale level. This was a "standard" oil that tested well, at a moderate cost. Omega vacuum refined petroleum based "semi-synthetic" was a super high-end 20-50. (about 4-5 bucks a quart 20 years ago) The winner was Redline synthetic multi-grade for street or straight 40 or 50 wt. for racing. (remember synthetic 40 wt pours more like 30 wt petro)

 They did serious testing in the lab and running engines on the dyno. One thing that synthetic did really well was gears. Don't forget that most "modern"motorcycles lube the transmission with the engine oil. A high film strength is needed there. Since we are lubing many of our PSRU's with engine oil I believe a synthetic is a good crossover oil that will work well in both. I like redline, but it's expensive in yank dollars I can't imagine what it goes for, or if it's even available in Oz. Motul is generally available worldwide but is also very expensive. I think Mobile 1 is a good oil for the price. Run redline if you're flush it's GREAT oil. If you have a separate gear reduction I would definitely run Redline in the gearbox. They make a truly superior gear oil.

Bill Jepson