I am going to rebuild the Buick's engine and transmission. The engine has the classic blown GM uper intake manifold. GM refuse's to fix it because mine was made 500 vechiles after the VIN break for that plant. Never mind that it has text book case of their fualty upper and lower intake maifold design. I did not catch it in time to and their is definately coolant leaking into the engine. Their has been no evidence of it in the oil until recently. I did find evidence of it under the oil cap . For right now I am just going to replace lower intake manifold gaskets and replace the entire upper intake manifold. This summer I am going to rebuild the engine and buy a reman'ed trans. I am going to test synthetic (Redline or AMsoil) oil and a bypass filter system and see just how far I can go with out an oil change!