I've been using Amsoil Synthetic oil since 1988; I use the 10W-30 weight now in everything. I have also tried the 20-50 and 10-40. It is a 25,000 mile or one year oil change oil !! I ignore the one year limit in my 2 family sedans, Saturn 4-door SL2's. I run it 25,000 miles between changes, and change the filters at 12,500. I add in between oil changes as needed. The cars have 197,000 miles and 167,000 miles on them, and I've owned them since 1995 and 1997. The stuff is great !! In a Pontiac, I would follow the one year limit. When I ran the oil in my '70 FB with 400, the engine was looser and revvy-er as soon as I changed it from regular oil.
|