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.
Car Problem Reports
Chevrolet Suburban 2500 Intake Manifold Gaskets May Leak Coolant or Engine Oil
Chevrolet Suburban 2500 Problem
Engines Affected: 5.7L V8, 7.4L V8, Gasoline
Average Mileage: 90,000 mi (80,000 mi - 100,000 mi)