The intake manifold gaskets can develop external engine oil or coolant leaks. The intake manifold will need to be removed and the gaskets replaced to correct this issue. In some cases the plastic intake manifold my be damaged requiring replacement.Google+
Car Problem Reports
Pontiac Bonneville Intake Manifold Gaskets Can Develop Engine Oil Leaks
Pontiac Bonneville Problem
Engines Affected: 3.8L V6, 3.8L V6 Supercharged
Average Mileage: 104,810 mi (34,000 mi - 223,000 mi)
Visitor, 2002 Pontiac Bonneville, 3.8L V6, 84,000 mi
Intake manifold leaking oil.
Visitor, 2002 Pontiac Bonneville, 3.8L V6, 76,000 mi
Noticed antifreeze level kept dropping. Would only see tiny amount on driveway not enough to explain amount being lost. Checked hoses, radiator, antifreeze holding tank no obvious leaks. noticed moisture on inside of oil fill cap. Went for annual inspection, mechanic found where antifreeze was leaking at top of engine and running onto exhaust burning most of it up before hitting the ground. Found upper and lower intake gaskets leaking. Replaced both
Visitor, 2002 Pontiac Bonneville, 3.8L V6, 223,000 mi
Loosing antifreeze from reservoir
Visitor, 2005 Pontiac Bonneville, 3.8L V6, 137,500 mi
Service engine light came on at 137500 miles. Car was diagnosed,will be fixed next week.
Visitor, 2002 Pontiac Bonneville, 3.8L V6, 148,000 mi
Slight loss of coolant (but no visible external signs). Recent issues with engine "bucking" when warmed up. Diagnosed at shop, will have gasket (s) replaced.
Coolant was leaking, had the upper intake manifold replaced
Visitor, 2004 Pontiac Bonneville, 3.8L V6, 90,000 mi
Oil leak on top of engine from vale covers.
Visitor, 2003 Pontiac Bonneville, 3.8L V6, 55,000 mi
Engine stalling and surging. Replaced intake manifold and cleaned throttle body and throttle position sensor (coolant had leaked onto TP sensor)
Visitor, 1995 Pontiac Bonneville
Lose in presure then cut off
Visitor, 2004 Pontiac Bonneville, 3.8L V6, 80,000 mi
I have had a slight oil leak for quite a while, and it seems to correlate with this common problem.