I think coolant is leaking into the engine of my '03 Olds. Sil. There's an orange foam on the oil cap and PCV. Any good stop leak or suggestions?

Stay with OEM. Do not use green.

If your exhaust smokes white ,which is steam when engine is warm this is a tell tale sign that coolant is leaking into combustion chamber of engine. If you see high level of oil or foam on oil dip stick, this a sign coolant leaking into engine. Either circumstance would mean possible blown head/intake gasket or cracked head or cylinder crack.
You can also have cooling system pressure tested to verify leaking, it is a quick test which is not expensive to have done at a shop.

you can purchase stop leaks, but i would have the vehichle checked out for a blown head gasket, or leaking intake manifold gasket and get it fixed right, hope that this has helped you.

it is getting sucked into the engine through a crack or bad gasket.
needs attention ASAP. take a sniff at the tailpipe for antifreeze odor, or look for foam on the bottom of the oil fill cap. ain't good.

Need to seal the leak in the coolant container with epoxy or by replacing the coolant container.

Fill coolant system with 50/50 solution up to 2 gallons may be required to stop the overheating.

Don't drive an overheated engine.

If you are putting in stop leak then yeah it goes in there because the radiator cap is on the overflow tank. But I wouldn't recommend using stop leak. The engine likely needs new intake manifold gaskets because that is a common problem with that engine. It would be better to just replace the gaskets

head gasket!

problem could be heads bolts . i put new bolts in put a little sealer on them . make sure your bolt holes is clean free from debris. put a lillte sealer on intake gasket on top and bottom where coolants travel. if all was done . drain engine oil in clean container .set it aside. take radiator cap off .you a coolant pressure rise kit .put a pan under oil pan with drain plug still off .pressure your radiator about 10 psi. make sure you have antifreeze in radiator and engine . when you pressure up to 10 psi look under the car if coolant comes out oil pan. you got leaking head gasket. if not .put oil pan plug back on . put oil back in car . check your freeze plugs also.

"I assume the chocolate color is an indication of maybe not water leaking into the oil?"
I'll lay $5 on it's being coolant :-)

As for the "overflow cap" or expansion tank filler cap as I would call it, in the absence of a VW engineer telling you different, I would leave it loose while the Stop Leak was taking effect, just to avoid forcing the Stop Leak into the oil system as the coolant system pressurised. If the can says "...works in ten minutes" then you could tighten it after that time.

Be sure to check the coolant level soon afterwards to find out if it has worked.

If the Stop Leak doesn't... I'd recommend getting a mechanic to find the leak and fix it. Left to themselves, things go from bad to worse.

Good Luck, D.

Hi, I would get other opinions, but it sounds to me like the water is getting into the oil system. This could be via a small leak in the head gasket, in the oil cooler (do you have one?) or somewhere else I can't think of. My best guess is that it is happening in the return side of the oil circulation system where the pressure is lower than that in the cooling system.

I would either read the label on the "stop leak" or speak with an experienced mechanic, or both, before using it. They might suggest running the engine with the coolant cap slack for a while to avoid pressure build up which might blow the stop leak into your oil system, with unpredicatable results.

When you have fixed the leak you might think about changing the oil or at least the oil filter. Hope this helps you a bit more.

Good Luck, D