Originally Posted By: TallPaul
If I changed the filter when it was cold, sitting overnight, practically no oil dripped so long as I didn't tilt the filter up. Not sure where the oil went from sitting cold. Maybe contraction when it cools?
If no oil drained out when cold, but you'd get oil out when hot, that's the perfect demonstration of the ADBV working (or not, in your case). It sounds like the ADBVs in your filters slowly let the oil passed against gravity. When changed hot, enough time hadn't elapsed for the oil in the galleries to drain back down to the sump against the ADBV. But after an overnight time period, all of the oil above the ADBV apparently leaked passed, and drained into the sump.