I just recently put in some mobil 1 5w 30 syn. In the owners man for my 92 anyway it says avoid high speeds when using this weight, why?? is it because the pump cant maintain enough pressure under those conditions to properly lubricate?? should I worry or what--------- and that is the correct oil for the climate here usually never above 75 in summer or 30 in the winter with the extreme days at about -30--60 actual air temp but avs in the teens, so unless anyone can recommend a better oil this is what I need and I should not speed. is this correct I need some response here,, thanks