Prefilling oil filters: not good?

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kilou

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Hi,

I found this here: http://www.widman.biz/uploads/Corvair_oil.pdf (page 19)

"You should not pre-fill the filter unless you do it from the outer ring holes. Any oil that goes into the center will reach the engine unfiltered (and there is no cleanliness standard for new oils)."


Does this make sense? I always pre-fill the oil filter when doing an oil change to avoid the engine running dry on first start. There are no outer ring holes on my filters (Volvo) so either I prefill them with unfiltered oil or I leave the filter empty.

What's the best solution?
 
you are putting clean oil into the filter. "No cleanliness standard for new oils" ?? To be perfectly honest it probably does not matter only probably slightly that you install a "filled" oil filter. In both of my cars, I have not noticed a difference whether filled or not.
 
Considering some engines go through their entire lives on unfiltered oil, the short time this would happen by just filling the oil filter is negligible.
 
So since there is no cleanliness standard on new oil does that mean it is dirty? I would think there is some QC and the finished product is gtg out of the bottle. I'd hate to think every time I change the oil I am filling the car with dirty oil.

AD
 
"Do whatever makes you feel best I guess."

+1. Thirty minutes of no oil pressure while the filter fills, or all the pea gravel I see in a brand new bottle grinding around my engine.

I'm going to strain all my new oil through a window screen, and then only prefill half to hedge my bets.
 
I've only been able to notice that the oil light on my SportTrac goes off a couple of seconds quicker with a filled filter. I suppose the minimal effort it requires to fill the filter is worth it in some small way in the shortening of a dry startup.

As far as new oil being dirty...hogwash. I've never seen any visible contaminants in my new oil, but as soon as I do, rest assured that it'll go back where I bought it from.

It's been my experience that the oil won't flow down into the smaller holes, so good luck with that.
 
simply...why not?

Do you enjoy running your fancy engine with no oil pressure while it fills the filter?

Admittedly a small amount of time, but as long as you can....
 
I dont know what difference filling the filter from the exit port with "dirty" clean oil will make considering that the other at least 3-6 quarts are going to be dumped into the engine without the benefit of filtration anyhow.
 
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The issue is insignificant in most cars and trucks. The filters are small enough and the pumps have a high enough volume that it matters little if you pre-fill the filter.
But some long haul and other diesel trucks hold around 40 quarts and have multiple filters, each filter holding around a gallon. Some of these filters are 6" in diameter and 12-18" long.
I have heard that some big rig companies sell machines to pre-filter the oil that goes into the filters upon pre fill, so that if you are using "bulk oil" it further guarantees that it is "filtered" bulk oil. Never seen one of these though.

On these large trucks with these large filters if you don't pre-fill the filters the engine will destroy itself the first time you turn it on. It takes too long for the oil to get from the pan through the filters, to the engine.
From what I understand it speaks of this at length in their maintenance manuals.
 
I've pre-filled them since the days of my 66 Falcon. I guess if dirty oil is a concern, you could put a spray paint filter in the funnel and pour the oil through that. I think filtered or not, pre-filling the oil filter is a better idea then starting an engine with a dry oil filter.

If I saw any junk in the oil I'd march if right back to where I bought it as well.
 
Originally Posted By: 97f150
I dont know what difference filling the filter from the exit port with "dirty" clean oil will make considering that the other at least 3-6 quarts are going to be dumped into the engine without the benefit of filtration anyhow.


+1
 
I often read here on BITOG about vehicles with 200,000 miles 300,000 or even over 400,000 miles on them. I'll bet that most of them never prefill the filter. Can anyone back me up on this?

If you have ever tried to prefill a hard to get to filter, you will never do it again.
 
Originally Posted By: kilou
"You should not pre-fill the filter unless you do it from the outer ring holes. Any oil that goes into the center will reach the engine unfiltered (and there is no cleanliness standard for new oils)."

As far as I know, most oil filler holes lead straight to the valvetrain. When you refill your engine after draining it, you're literally pouring "unfiltered" oil straight onto the moving parts into your engine. If that isn't a problem, I can't imagine it'd be a problem to pour oil into the little hole in the middle of the filter.

EDIT: Sorry for stepping on your toes there, 97f150. Didn't see your post.
 
Maybe we should prefill our filters and the crankcase by pouring the oil into the outer rings, installing on the vehicle, cranking for a few seconds, than take the filter off again and repeat until the crankcase if full. This way all of the oil ever put into our engines are prefiltered.
 
I only prefill my 2qt filter on my small block with 1qt of oil all the others go on dry
19.gif
 
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