To recap my recent coolant-in-oil "mystery", UOA indicated coolant in the oil from my 1999 Suburban 454 but the mechanic I took the truck to could not find (or did not recognize) any signs of the common intake gasket problem. Also did not find signs of head gasket failure. Cooling system pressure test passed. So my plan is to drive it normally (which is very little) for a while and sample again after maybe 500 or 1000 miles (which probably means 6 months). Obviously I want to keep an eye on things in the mean time. I'll keep an eye out for milky oil, and monitor the coolant level and see if it goes down, but I wanted to know exactly what I should look for with respect to the intake gasket. The mechanic told me I should look for coolant residue on the front of the engine around the bottom of the intake. Will they always show externally when there's a leak? To be honest the engine is pretty grimy so it's not even going to be extremely easy to see coolant residue. Is there anything else I should be keeping an eye on?