Straight to the point, always ensure the old O-ring is removed before installing a new oil filter, and double-check Adjust Full-Screen Ratio In Alight Motion the oil filter mount. I learned this the hard way 40 years ago when a double gasket failure happened in my driveway instead of a customer’s car—an experience I won’t forget. To avoid future mistakes, I place a rag over the hood latch with the oil fill cap, so I can’t shut the hood without remembering to fill the oil and replace the cap. It’s a simple but effective trick I picked up from an experienced mechanic.