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
Chevrolet G Series Van (G30) Intake Manifold Gaskets May Leak Coolant or Engine Oil
Chevrolet G Series Van (G30) Problem
Engines Affected: 5.7L V8, Gasoline
Visitor, 1995 Chevrolet G Series Van (G30), 5.7L V8
The manifold gasket leaks onto the transmition bell housing. I haven't fixed it yet.