nycsteve - I have always used full synthetics in all my vehicles and race bikes (I raced GNCC and hairscrambles). I cannot recall the exact difference between the reg. and premium snth blends, but with some research I am sure you find the difference between additives, and volume contained in each.

IMO - the synth blends are a waste of money but some people just can't bring themselves to spend the extra money on a full synthetic. I never had good success with the blends that I tested in my bikes. However, I have had great results with Mobile 1 full synth with a little bit of Lucas oil stabilizer added. I cracked a case during one race and I managed to finish with no oil left in the crankcase while using this combo...and yes there was some damage but nothing seized. I have used this combo successfully in my race bikes for the last 5 years and it has showed the least breakdown of all the oils I tested. The only other oil I would recommend is AMSOIL but it is a bit pricey.

I am sure you have heard it before....but oil is cheap insurance against failure. After my first oil change, I plan on using the Mobile 1/Lucas combo for the life of the vehicle.

Regards,
Rick