Jussi U

This is an AI answer and I the later is the cheap way to check first. Worn Piston Rings (Blow-by): If the piston rings inside the engine cylinders wear down or crack, combustion gases can leak past them and straight down into the oil pan, over-pressurizing the crankcase.Worn O-Ring: If the engine pressure is normal, the rubber O-ring on the dipstick itself might just be dried out, shrunken, or worn out, meaning it no longer grips the tube.To troubleshoot, inspect the rubber O-ring on your dipstick to ensure it's snug. If it is, or if you also notice rough idling or smoke, have a mechanic check your PCV system or perform an engine leak-down test.