I've dealt with lawn mowers for most of the 78 years of my life but had something happen I've never had before. The oil filter came loose off the motor. I always believed you were to hand tighten the filter and not wrench it on however when I drained the oil and changed the offending filter and added a new filter and oil, the same thing happened. I finally took it to the dealer and was told the new one was loose again. The mechanic also said for the past several years he's noticed this more and more. He wondered if they were using a different rubber ring or something. His instruction was to had tighten and then turn 3/4 of a turn more with the wrench. He did add that sometimes you'll have a hard time getting them off. The mower is a Simplicity Broadmoor with a Briggs and Stratton Motor.