Are you sure it's oil? The filter extension is water cooled. There are two rubber hoses running to it (one is called the "J hose" around here). When the filter gets changed, oil dribbles down onto these hoses, disolving them somewhat. Common places for coolant leaks. They are an easy fix, one is even connected to a little drainvalve for your convinience. Hopefully someone else will know their real names-in the dealer's book they are on the same page as the filter assy. While you're at it, replace both heater hoses, radiator hoses and other plastic/rubber cooling parts (incl heater valve). They (and the radiator) seem to have a 10 year life cycle. Sudden leaks stranded my '92 this summer (no damage, luckily). Hope this helps.