I recently was offered the chance to buy a 1972 280 SEL 4.5 that had not been operated in 5 years, and I thought it would be a good opportunity to teach my 15 year old son how to work on mechanical things and how to use tools. I spoke to the mechanic who services my cars (and is an American car collector) how to prepare the car before attempting to start it. I did all that and it runs great, but after changing the oil filter there is a slow leak when the engine is operating at the bolt head that retains the canister housing; the seal at the block is not leaking. The bolt has a steel washer on the outside and has a washer/spring arrangement on the inside to position the element. The new (Fram) filter element has a rubber seal on each end, with the large one toward the block; it appears to be identical to the one I removed. I have changed enough car and motorcycle oil that I thought this would be the easy part of the job but as I tell my son, there are always suprises. I would appreciate any suggestions.