What kind of oil?

[burgundy83]

I've got a 1983 Cutlass Supreme with the 305 Chev in it. Wondering if I need 5w30 or 10w30 or something else? Oil cap says nothing, no manual.

 

[billyjack]

According to the 1986 Olds factory Service manual, 5W30 is the preferred viscosity, with 10W30 suitable for use at temps over 0 degrees F. If it's a year-round driver, I'd run 5W30 in below freezing temps, 10W30 the rest of the year. I use only 10W30 in my Camino 305, but it's parked and garaged all winter.

Bill

 

[outsider_27]

I use 10W30 all year long. 5W30 is too thin for older engines and will find new places to leak out.