5w 30
 

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:) :)

5W-30 would be good in the winter but not in the summer. The highest contact pressure is between the cam and the lifters and then the rings sliding in the cyclinders. The oil is cooled in that hugh oil pan on the bottom of the car. Cooled by the air around it. In the winter the oil is colder and as the chart shows a thinner oil is okay. In the summer it should be thicker. A minimum viscosity at operating temperature is required to keep the metal parts from contacting.

Use a thicker grade in the summer and a thinner grade in the winter.