What Grade Oil to Use>>w30/40 etc..?

Ok my gal is a 95 4.6L V8, with about 122,550 miles on her. I went to Avis, and they used 10 w40. I am gonna start doind my own changes, and would like to know what yall recomend on a high mileage engine like mine. What grade will be better for my car also, 10w30/w40 etc.

I've always had luck with Mobil-1 Synthetic, 10-30 equivalent. But that API rating should be changed depending on what climate you live in, and how you drive your car.

I've always had luck with Mobil-1 Synthetic, 10-30 equivalent. But that API rating should be changed depending on what climate you live in, and how you drive your car.