I recently bought a 2000 Grand Prix with a 3.1 V6 and 100K miles. It has oil residue in the coolant bottle and a white film skim in the radiator. I have read a lot on here about LIM gasket failure, but I want to make sure I have all the info I need before tackling this job. My question is this: I do not have any signs of water or antifreeze in my oil, what other signs should I look for? The dipstick is clean and so is the underside of my oil filler cap. Should I flush my coolant and just keep and eye out for the thing to "make" oil capacity, or would you assume that there is a gasket failure and change them anyway. Any help would be greatly appreciated.