i have much experience with royal, i wouldnt use it until you get 5000 miles that stuff is too good, & it wont allow the rings to seat properly on a new engine. give it a while before you use it. use the weight spec'dggreenly said:Thanks for the info. Do you have any suggestions re which of the synthetics to choose from. I have a contact at Royal Purple Synthetic lubricants, out of texas. Anyone have any experience with this product? Also what weight oil is recommended?best??