The intake manifold gasket may develop and external engine oil or coolant leak. In some cases, an internal coolant leak may occur causing coolant to mix with the engine oil. Running the engine with a coolant/oil mix may result in engine damage. Replacing the intake manifold gasket should correct this issue.Google+
Car Problem Reports
Pontiac Grand Prix GTP Intake Manifold Gaskets May Leak Coolant or Engine Oil
Pontiac Grand Prix GTP Problem
Average Mileage: 119,419 mi (47,000 mi - 160,000 mi)
Visitor, 2000 Pontiac Grand Prix GTP, 130,000 mi
CONSTANTLY ADDING COOLANT
Visitor, 2004 Pontiac Grand Prix GTP, 147,000 mi
Constantly having to add coolant, also had white smoke under hood. Found external oil and coolant leak. Cost of repair $1300
Visitor, 2004 Pontiac Grand Prix GTP
These engines generally do not blow the head gaskets. White smoke came out. I thought it was a blown head gasket, but the car only has 62,000 miles on it. It was the plastic lower intake manifold gasket. This one is the supercharged model. Get the metal gasket, do use the plastic ones as you will have the same problem later. Merle Gebers
Visitor, 2004 Pontiac Grand Prix GTP, 83,000 mi
engine leaking coolant and oil from intake manifold, car slightly runs hot in traffic and idling. changed thermostat, changed radiator cap,bled air out of cooling system,going to replace intake upper and bottom gaskets,this should stop leak, hope it solves heating issue.
Visitor, 2004 Pontiac Grand Prix GTP, 80,000 mi
Losing coolant and oil, problems starting and a rough idle.
Visitor, 2000 Pontiac Grand Prix GTP, 97,452 mi
oil in coolant but no coolant leaking into the oil
Visitor, 2004 Pontiac Grand Prix GTP, 47,000 mi
oil and coolant leaks, external,
Visitor, 2002 Pontiac Grand Prix GTP, 122,000 mi
losing coolant and oil with no visible leaks
Visitor, 1997 Pontiac Grand Prix GTP, 137,000 mi
I have an Intake leak.
Visitor, 1999 Pontiac Grand Prix GTP, 126,000 mi
Intake Manifold Gasket is also leaking. Estimate for replacement - $840.