I had a chance to talk almost half hour with a Motul R&D personnel at Indy GP (he is not a product specialist, he was the real shit, gave me his card as well). This is my sum up: Best from the top 1. First (Grade V) Double Ester motorcycle synthetic, very expensive like Motul 300V, the motogp guys are runnung 5W40, you can use 10W40 or 5W40 (this he recommends). Points: a. The double ester bonds on the metal surface electrostatically and you will never rub metal to metal even in cold start b. It absorbs water and increases the detergent action. c. Even if it burns, it almost provides no residue. It can be used upto 277F. d. It does not suffer shear loss in extreme conditions. Big Question (The guy's view): Do you need this for a street bike ? Really no. But do you really need a Lambo or Ferrari to go from point A to B, a Civic will do that too. So if you want the best spend the money....because you can. 2. Grade V, Poly alpha olefin (PAO) and Ester mix, expensive, like Motul Etech 100 or Mobil1 Racing 4T. 3. Grade IV PAOs, most other synthetics....all brands are just fine for your daily requrements. Most will not tell you what is in there, you have to find out from the material safety data sheet (MSDS) which is usually available from the product website.