1995 Chevy Lumina

Hi, I have a great reliable car in excellent shape, both the exterior and mechanically. However, yesterday when checking my antifreeze/coolant level in the overflow tank, it appeared to have a slimy substance on the surface. I thought perhaps OIL…so I dipped a stick in and felt the substance which did feel a bit slippery.

Could oil have mixed with the antifreeze/coolant?

If so, what would be the best and worse case scenarios???

Thanks so much.


It seems you have discovered a common (but serious) problem.

It’s better known as a leaking intake manifold gasket common to GM engines for a number of years in which your year of vehicle was the first. Actually from '95 to '03. Guess what? NO recalls.

Have a coolant pressure test done now, don’t wait.

If, indeed the coolant is mixing with the engine oil damage is already starting.

Engine oil diluted with coolant strips the lubricant and finish off of the crankshaft journals and eventually the engine will seize.

Sorry for bad news, but if the coolant hasn’t been leaking for long, (as in, just started) you may get lucky.

Have a look on the bottom side of the oil filler cap. Is there a brown milky substance there? If so, that’s an indicator of a leaking intake manifold gasket.

One point I would stress here is you ensure the new gasket kit replacing the leaking one is the kit GM released after Feb/'03.

The GM kit # is/was on this website sometime back, but I doubt we’ll find it since the swap fest here. Perhaps someone has it written down.

Oh noooo…soooooooo, I presume I take it to my mechanic for a Coolant Pressure Test. If the coolant is indeed mixing with the oil…how much do you think it’d cost to repair such an issue?



This could be the part list Roadrunner was referring to, if GM’s kit is the same across model years. But anyway this link gives you a idea of the problem http://www.naioa.com/v2/modules.php?name=Forums&file=viewtopic&t=3354

Get it checked out immediately, but don’t lose any sleep yet. By your description, it could be anything. Ethylene glycol coolant is slippery even without oil. Lots of coolant bottles have some sort of slick on the top with no problems. Has the coolant been serviced as recommended by GM?