I remember back in 1980 I bought an iron head Harley Sportster. At that time Harley had just come out with their own 20w-50 oil and recommended it for my bike. Shortly after getting the bike I took it on a 400 mile run in temps over 100f. On the way back, I started hearing a metal noise coming forum the top end. It would stall on me but start back up. I took it to the Harley dealer and they told me there was nothing wrong with. As a diesel mechanic by trade I had no problem working on the bike, the engine was pretty simple compared to what I was used to. I found that one of the valve guides had worn so bad the valve was slapping to one side before it would seat. This could of only happened because of multi-weight oil viscosity failure. I rebuilt the heads and from then on I ran only 50wt. oil. Never had another problem and I put 70,000 miles on it.
Being on the Rhino forum I see a lot of engine failures and everyone was running multi-weight oil. The wise ones would change it out after a weekend of hard riding, but I am first one who has ever done not one--but two oil analysis at 50 hour intervals. The Yamaha manual says I should only change the oil ever 300 hours after 150 hours. If I would of listened to them I would have an engine failure before 300 hrs. Now I don't listen to them or buy their over-priced oil and filters. I will continue to conduct oil lab tests on the forty weight at short intervals to do a comparison to the multi-weight.
Thanks for your support.
--Geoff
