Oil Filter Anti-Drain Back Valve

If the filter is mounted vertically with the threaded end oriented up is this valve important? I would assume the filter would remain full with no anti-drain back valve.

Is the valve trying to stop back flow from all the oil passages on the outlet of the filter?

What happens if you drain the oil but don't change the filter? Does the oil beyond the filter stay in the engine?

If you drain the oil in the sump and replace the drain bolt and then remove the filter does additional oil flow into the sump after the filter is removed?

Should you wait on installing the drain plug until after you've removed the oil filter?

No filter is full.

No. It can't it's not a pressurized system unless oil pump is pumping. Bleeds out at bearings.

Some but not much. Plus whats in the filter.

Not on a filter that's threads UP.

Depends on how much BS you read on internet. Slow night?

Must have finally finished playing all his Beetles albums in reverse......

I don't get..

Are you looking to put a FRAM oil toilet paper oil filter on your FJR?

Sorry, just don't understand the question..

??? ???

This is about one of my cars. The filter is mounted vertically with the threaded end up.

On a forum about the car many like to comment about their oil filters just as many do on this forum. They seem to be very concerned about anti-drain valves and their material of construction.

I wondered if the valve is irrelevant if the filter is mounted so that it stays full.

I've noticed on the FJR after removing the filter that oil continues to glug-glug out for some time. So the filter must be holding back oil downstream in the cooler, etc. Maybe the anti-drain back valve has value.

Many filters have a rubber flap over the intake holes that is an attempt to keep oil in the filter and minimize the time it takes to fill the filter when you start the engine (they call it an anti-drain back valve). A test you can perform to see how well this “valve” works is to fill a filter with oil, plug the large center spin on hole with a bolt, lay it on it’s side and then see how long it takes for the oil to drain past the rubber flap. We have found (and have read other published tests) that the filter eventually ends up with the same amount of oil in it as if it didn’t have the flap, it just takes longer to drain out. If the flap worked as planned it would be beneficial to have the extra oil in the filter at start up. On the other hand, that flap covering the intake holes is one more restriction the oil has to get by to get through the filter and back to the motor. All of our testing shows the K&P Engineering filter with it’s ultra low resistance to flow builds oil pressure in the engine components faster than a paper filter that has the anti drain back.

Threads up stays full. Any other position it can drain back into oil sump.. AND it will even with a good anti-valve just takes enough time. A better one is ideal at engine start up oil pressure comes up faster= less engine wear when filter is full. It's only a second or two until pump fills it up, longer with cold or thicker oil.

I always fill an oil filter before installing it. Anal.