I have the same 4.8L engine and 4L60 w 183k miles. Use 0,5 or 10w30 in any brand u prefer. Conventional, blend and syn will work. I prefer the longer AC delco oil filter. Right now I have Pennzoil Ultra 5w30 in the motor w delco filter, Valvoline MaxLife ATF w wix transmission filter, supertech 75w90 in the diff, supertech power steering fluid, supertech dot 3, valv multi purpose grease in the fittings, OReillys orange dexcool, fram air filter, micro guard cabin filter, techron and marvel in the gas and Nu Finish on paint. no piston slap, no leaks,runs good. Enjoy ur truck.