pre fill oil filter?

haven't seen this brought up here before so what are your thoughts on prefilling oil filters it seems just about everybody gives a different answer

Why wouldn't you?
It's not like it's in hard to reach spot or sideways.


Rock

There's definitely no harm in it. Builds oil pressure faster on startup.

Can't really do it on engines where the filter mounts sideways though.

I change a lot of oil, because part of my job is taking care of a fleet of trucks and equipment. The way I look at it is if it’s a large filter and easy to get to, then I pre fill it. I use the same strategy for fuel filters as well. So by that logic I pre fill both on an IDI. But for instance on say a older duramax I don’t do either. The oil filter is horizontal, and the fuel filter is easiest if you drop the passenger inner fender and go in that way (it looks a bit like you’re pulling a calf when you do it). On most of my gas trucks the filter is so small (holds about a pint) I just don’t bother. I also have a few diesel generators with Isuzu engines. They run a ridiculously large oil filter (it’s bigger than the PSD filter) but it’s mounted upside down.

The argument against is most of us put the oil in the "big hole" in the center of the filter, which is actually the exit, thus you feed the engine a slug of unfiltered oil they may have some contamination (dust in the air, etc) in it... while leaving it dry forces the new all the new oil from the oil pan to go through the filter before going to the engine.

FWIW, I fill my filter first.

I don't.
The IDI has a high volume oil pump, it's designed to be able to run and supply auxillery equipment such as an air compressor. It pumps between 0.1 - 0.3 gallons per second depending on rpm. If you hook a manual gauge to the engine and put the oil filter on dry, you'll see the psi comes up within a secondish of it firing.

Every. Single. Time. I dont see a reason NOT to. If I dont change the air filter I also blow out the air filter & spray the radiator from the engine side, out. WE have hellacious dust storms and I some times drive through tall vegetation. So far , so good.

My oil filter holds 3 quarts so yes I pre-fill, wait, does that mean I fill it before I fill it?

Not worth the effort if you are changing the oil warm. There is enough film on everything to protect for the 1-2 seconds it takes the filter to fill and get back up to pressure. Just don't rev until the pressure is up.

As jrollf said unless you only fill the outside you are putting unfiltered oil into the system which can do more damage than the couple of seconds of startup.

I always fill the FL-1995 filter when Replace it.
Proper way would be to pour the oil into the outer holes,
Which would take for ever.
When I fill it through the center big hole, Iam dumping it
in from a clean factory filled container. But I suppose any
contamination that could drop into the big hole can`t be
ruled out.

The Filter when you open the box, is not wrapped in anything. just an open Filter, and dust/dirt through all the
shipping and handling could have entered it...who knows?

Same with the Fuel Filter, fuel comes out the big center hole and then to the IP. Any contamination here is more critical.
So yeah, I fill the filter the same way, but fill it with ATF or MM oil from a clean bottle.

Which ever way it has been done buy us or prior owners, the engines still run 300 - 500K miles.

Blowing out Air Filters can be bad, too much air pressure and holes can be blown through the paper. Also dust blowing around "can" float around to the inside of it if not careful.
The filter I use (Wix?) has the foam outer pre filter cover.
I pull it off and replace with a spare clean one. Then wash out the removed one. amazing how much it collects and keeps the paper one clean much longer. I have used low air to blow through them just to see if anything comes out and usually nothing the eye can see.
And here is the area of Nevada we are in is dusty, and we are on a dirt road.

Kind of like fore play, stick it in, s-crew it down and fill it up and move on.


Goat

So....all this malarkey about filling a filter with unfiltered oil....how does that work???
You are dumping 10 quarts of so called unfiltered oil in the crankcase and you are worrying about the 1 quart in the filter???
Learn me something, huh..


Rock

Well I've always just liked to fill filter mostly up then put on.
I get sort'a mad at me if I mess up & drop filter on my face though.

ttman4 said:

Well I've always just liked to fill filter mostly up then put on.
I get sort'a mad at me if I mess up & drop filter on my face though.

Click to expand...

i have had that happen once. It was terrible. Oil everywhere.

Yep you are putting unfiltered oil in that goes directly to the bearings via the big hole when filling
BUT unfiltered oil does a far better job lubricating bearings than no oil which for the first 3-5 seconds you won't have any oil feeding the bearings
Yes they have a high volume oil pump, but your asking it to fill 2quarts of oil before lubricating anything
Cummins also asks you to prefill their oil filters before putting them on. Doesn't specify filling small holes either.
Yes it is a trade off ... but fill it with oil before hand

Farmer Rock said:

So....all this malarkey about filling a filter with unfiltered oil....how does that work???
You are dumping 10 quarts of so called unfiltered oil in the crankcase and you are worrying about the 1 quart in the filter???
Learn me something, huh..


Rock

Click to expand...

Well, if I am looking at the oil flow correctly, the oil pickup / oil pump draws from the pan, then the oil flows into the front header for the oil cooler, through the oil cooler (so that means the oil cooler is cooling unfiltered oil) to the rear header, which has the oil pressure regulator, pressure bypass and the oil filter. It leaves the filter and then enters the main gallery, then flows through the engine, from the bottom to the top, and then is returned to the pan. Then it starts all over again. This means all the new, clean unfiltered oil you have poured into the pan, gets filtered before it enters the oil gallery to lube the bearings and all the other tight tolerance stuff…



As for me, I put the filter on, empty, on everything. The only thing I really worried about pre filling was the IDI fuel filter, so as not to get much air in there. On some, as said, your can’t pre fill due to location. Or, like my 6.0 has cartridge style oil and fuel filters. They way the oil filter housing is designed, there is a drain that is opened when you remove the filter to allow the oil in the housing to drain to the pan when you replace the filter. So it you try and prefill the housing, it would just empty out anyway. Most filters will fill fairly quickly.