ZuffenZeus

Porschetech3

Yes, it matters greatly ....during routine maintenance it doesn't really matter because the oil pump gears are wet and a lot of oil still remains in the system..

But after a rebuild, there is no oil except where oil is put during assembly ( or assembly lube) and the oil pump gears are dry ( unless you intentionally lube them) so putting on a pre-filled oil filter can create a slight "trap" that a dry oil pump will have difficulty in pushing through..

Let me show a visual and get a little deeper into the physics..



The red X is a 1 inch channel from the oil pump inlet that goes back half way of the engine then down to the bottom of the Sump

The yellow x is a 1 inch channel that goes all the way to the rear of the engine then down to the oil filter

From the oil filter a 1 inch channel goes up to the top of the engine to the oil cooler before going back down to the main oil galley that feeds all the bearings and heads..

The green line represent the oil level when filled.

During routine oil changes all of this is wet and a lot of oil is still everywhere even though a lot of air does get in, the wet oil pump has no trouble pushing air though and atmospheric pressure pushes oil up to the oil pump gears and the system is "primed"...

But after an engine rebuild, all of this dry, the 1 inch channel to the bottom of the Sump ( red X) ..the oil pump and gears , the 1 inch channel (yellow X) all the way to the oil filter..all is dry....So IF you install a pre-filled oil filter it creates a bit of a "trap" ( like a "P trap" under the kitchen sink) and when you fill the Sump with oil, the oil will not even go up the pick-up tube to near the pump ( the green oil level line), the oil will not even go up to the oil fill line, it will be empty all the way to the bottom of the Sump ( unless you fill the Sump first, then install the pre-filled filter, but then the pump gears are still dry.)and the pump gears being "dry" will not push air through the wet oil filter media (unless it is turning at a high RPM or has been wetted or lubed or packed with a petroleum jelly.).so if you start an engine like this it will not build oil pressure untill it is too late..

So there is a lot of things going on and many ways to slightly help or hurt the situation..

Air can be pushed through a dry filter media easier then it can be pushed through a wet filter media...

AND if you just install the filter dry ( not pre-filled) and start the engine ( not just spin it with the starter because the starter RPM is not quite enough to push the air out) the pump will spin fast enough to push all the air out and prime the system.

There are many ways to skin a cat, and Technicians know many ways fix a car ( ie. easiest/ safest/best but more difficult/best but more risk if not done to the "t")

wdb

It is still inconclusive. Unless he follows the prefill test with a no prefill test that finds bearing material, he has not proven anything.

996C438

Not sure if you are serious or not but I LMAO when I read it . If it was an attempt at humor well done 😁

Porschetech3

I know right ? This forum loves to take two giant steps backwards technically to take one baby step forward.....

ltusler

Thanks, yes, I should have used the green text color.