Detail: Oil mixing with coolant.Car is overheating, coolant is tan.Had radiator tested.It's not trans fluid.Oil level fine and no coolant in oil.Oil on top of heads look fine.Buick park ave 150,000 miles 1998 supercharged
Solution: If this is a 3800, Upper Intake Plenum or Lower intake gaskets are an inevitability. Head gaskets on these engines rarely go out! Seriously, don't get duped. I am doing the job on my grand prix right now. Google it for further explanation. , Possible Head Gasket Problem As OIL PRESSURE is ALWAYS Higher that Cooling System Thus Allowing OIL to Get into Coolant , Hi, a 6ya Mechanic can help you resolve that issue over the phone in a minute or two. Best thing about this new service is that you are never placed on hold and get to talk to real repair professionals here in the US. click here to Talk to a Mechanic (only for users in the US for now) and get all the help you need. Goodluck!