There are three (sometimes four) ways for oil to get in and/or out of a canister filter: The lid, the inlet fitting, the outlet fitting and on some with that feature a drain plug on the bottom side. The only way the oil could get out the bottom is if the canister has the plug and someone removed it OR the outlet fitting is missing. If you have a canister with the threaded hole on the bottom (slightly offset from center) you'll need a 1/8" NPT plug. If you have a hole directly center on the bottom that's the outlet. The thread is the same as the plug. All of that is for the Fram canister. Other models may be slightly different.
Last edited by Tiny; 03/24/2015 4:05 PM.
