What is the right oil to be putting in to a 1992 Buick Roadmaster?

I have a 1992 Buick Roadmaster with the 5.7L V8 and the car has 180,000 miles on it currently. I have been putting in Pennsoils 10W-30 normal motor oil and I would like to know if this is ok to be doing. I have been doing this for a few years and just want to make sure that the car is ok for this weight of oil and if it should have a thicker oil or thinner oil and what that oil would be?|||10W-30 is fine for warm weather.|||The thing here is to read the container that holds the oil you are using. It should state here that this oil "meets or exceeds GM specifications." If I were you, i wouldn't use anything but synthetic. Pennzoil Platinum, "made for GM" is very good. It cleans the engine while you drive instead of forming sludge. I would also consider having your engine de-sludged first. Basically, Pennzoil is a great oil. Greater than most on the market, in fact. But their "regular" oils make deposits, just like nearly everyone else's. There costlier oils provide better sludge protection and detergency to protect engine seals from leaking. Personally, I would rank Mobil One "0W" oils, ELF and Amzoil higher up in scale. Try Amzoil crankcase cleaner, first.