Milky coolant.

[thstone]

Two quarts of coolant + two quarts of oil is a lot. Its going somewhere, so if its not leaking, then its going out the tailpipe.

I'd start with a close inspection for any seepage or leaks that might be evaporating before they drip - especially around the water pump and water/oil cooler on the top of the engine. If that doesn't turn up anything, then I'd pull the oil filter to check for debris (leave the oil in the sump). If nothing shows up, I'd do a pressure test of the cooling system. If that is good, then I'd do an engine compression and leakdown test. If compression and leak down are good, then I'd remove the water/oil cooler and pressure test it just to be sure.