Well your friend is right, from my experience and other fellow riders like myself, we swear by AMSOIL which is what most use. Its for high- stress motorcycle engines and transmissions and its really the best that is out there in my opinion.
I agree with GhostRider on this one, I as well as anyone that I know that has a Harley will not use anything but Amsoil in our bikes. I have used this in my bike since the day of purchase in late 1997 and I have never had any regrets.
actually, if you use premium synthetic motorcycle oil like "amsoil" there are some benefits. the engine runs cooler, extended drain intervals and longer service life. Synthetic motor oils offer numerous performance advantages over the regular petroleum based oils. But i dont know most of the riders discouraged from embracing synthetic oil trend.
Yup, synthetics are definitly better than others, They actually did some tests on some popular big name brands and some were way better in some area's, If I findthe link to where you can find the study, I will post it shortly.
I have a friend who bought an older bike from another friend. The bike never leaked when it was run on a regular basis, but if he let it sit for awhile (which he did after buying a newer one) it would leak.
The friend that bought the bike switched to synthetic and the leak disappeared and has never come back.
Why is this? Because synthetic oils swell the seals (sort of like the old trick of adding trans fluid), however once you switch to a synthetic oil (whether in your bike or car) you can never go back to regular oil. Why? because the seals will shrink beyond their normal size and cause you major leaks.
In my experience with my 1200 Sportster, the synthetic DID make it run cooler (something you need here in FL during the summer months) but made the valve noise in the upper part of the heads much more noticable.
If you run for 5000 miles between changes, which HD now recomends, then switching over is probably a good idea. I used Amsoil in the Sporty, but I think with the new bike I will proabbly go with Screaming Eagle brand. HD says that you can use Sreaming Eagle brand in both engine and trans.
ALSO if you ever need to add a differnt brand of oil at some time other than what you are currently running (say your on the road and are running low) you should change your oil as soon as possible. Different oils have different mixes inside and and mixing the mixes can cause a chemical reaction inside your engine (not good).
In any case to use or not to use synthetic is purely a personal choice.