The Walk-around Inspection

You’ll find the oil filler cap somewhere on the valve cover. If the engine is a longitudinally-installed V6 or V8 the cap could be on either valve cover, if the engine is a transverse installation, the oil filler cap will always be on the front valve cover. Some oil filler caps on older vehicles have a hose running to the PCV filter in the air cleaner housing; later caps have no hose but are clearly marked. Always make sure the area around the opening is clean before unscrewing the cap to prevent dirt from contaminating the engine.

Check the Oil

Find the oil filler cap. It’s almost always located on top of the valve cover on inline four and six-cylinder engines, or – on one of the valve covers on V6 and V8 engines. Unscrew the oil filler cap turn it upside down and look at it. The oil may look brand new. Don’t be surprised. Sellers often change the oil before putting a used car on the market. Or the oil on the bottom of the cap may look used and even dirty, but that’s okay. What’s not okay is the underside of a cap coated by a light brown frothy sludge with the appearance and consistency of a chocolate milkshake! There may also be small droplets of water or coolant mixed with the oily sludge. This condition indicates coolant has gotten into the oil from a failed gasket, or worse yet, a cracked cylinder head or block. Whatever the case, the vehicle should not be driven far, or at all, until the condition is repaired.