Northstar Engines and System Technical Discussion Discussion, Can i use synthetic oil in northstar? in Cadillac Engine Discussion; I have a 2003 STS with a northstar engine, i wanna know if i can use synthetic oil inside this ...
Your owner's manual recommends 5W-30 oil for everything other than HOT climates. Mobil 1, Pennzoil Platinum, Royal Purple, whatever floats your boat in a name-brand oil.
I use exclusively Pennzoil Platinum 5W-30 and a WIX 51522 filter, change oil every 6000 - 8000 miles and get about 3,500 miles to the quart; town, country, highway, crazy driving. Look down into the chaincase with a flashlight, through the oil fill cap, and it's absolutely new-metal clean.
Read the oil article up ^^ there in the archives/technical. You have reopened Pandora's Box.