Originally posted by thompsonian
Just to be on the safe side, I run Honda GN4 in the 929. What the manual called for, so that's what I use. Unless I'm out in the middle of nowhere and low on oil, then I had to use some Castrol. But mainly GN4.
Funny you post that. Synthetics have advantages at extremes and are less vulnerable to contaminants in short run vehicles but frequent changes, 3,000 miles or 3 months, will afford very good service life on regular oil. GN-4 Honda oil is what's been run in my bike for 90,000 miles and it still runs like new. In the seventies, I put 143,000 on an air cooled 750 running nothing but Castrol GTX. That engine still ran OK.
I tried Honda's synthetic in my current bike around 50,000 miles and did have clutch slip problems so I changed the clutch and went back to GN-4. I have the same concern about GTX, using the friction modifiers, so haven't run it, just stayed with Honda's oil.
BTW, my current bike turned 89,000 while on the track and the older 750 was drag raced. Point being, they get run, not just putted around. They get good maintenance and get fully warmed up before to run hard, but they see red line with some frequency.
While there's certainly nothing wrong with synthetics, I'm not sure the extra expense is really worth it. Spend the difference on brake fluid changes and other maintenance items often overlooked.