Originally Posted By: Bluestream
If the filter is mounted horizontally, the oil cannot drain out unless it can defy gravity and get sucked up and out.
In this configuaration any filter (with or without anti-drain back) is going to work the same.
Anti-drain back is designed to work when the car is off, not on. It keeps the oil from drainingou of the galleries and back to the pan
ADBVs are beneficial in filters mounted vertically and horizontally. Doesn't matter the orientation. Even in vertical-mounted filters, head pressure above the filter can force oil back down, and the filter can actually siphon itself dry.
I had a Nissan truck back in the day, and if you didn't use a filter with a good ADBV, you'd get a lot of noise on start-up. And yes, the filter mounted in the conventional vertical position.