[cadillac_al]

Yes, I think 15-40 is too thick for your 60,000 mile car. I only use it in mine because it is old and loose. The high mileage oils have extra zinc and other anti wear additives. If it were mine I would use a 10-30 oil; I don't know if you even need the high mileage and a synthetic 10-30 might be fine too. When you mentioned 5-30 it kind of sent up a red flag for me but since you explained your oil pressure even the 5-30 might have been just fine. I'm amazed at how nice mine runs with 190,000 miles and it doesn't even smoke or use oil. The only time it had me worried was when the oil light flickered with the 5-30 but it was just showing it's age a little but it's all forgotten now. Yours should live a long life.