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Filling oil filter when changing oil?

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Well seasoned school bus mechanic tells me when they get somebody new changing oil it's only about 2 weeks till they stop filling up new filter with oil before threading on new filter without prefilling.  Interesting part to me was no failures that he knows of.  I fill mine but wondering if really necessary. Other than manual says so.  

Do you prefill?

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I won't do it. Anything poured in the center hole debris wise is straight to the bearings and oil jets. You would have to hold your thumb over the center hole and fill from the outer. 

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I used to but stopped a vew years back. The wifes Saturn has a horizontal filter so ther is no way fill it. I have never experienced any harm from it that I know off. I also have not noticed any difference by not filling it either. The engine builds pressure just as quick after a change as it did with a full filter. I am also not disagreeing with what @Mopar1973Man is either.

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I don't pre-fill either, for the reasons that Michael mentioned. 

 

The oil filter drains back about 1/2 anyways so it's really not much different than a regular cold soaked start. 

 

I monitor pressure on the drivers side of the block, well past the filter, and the difference in time to build pressure after an oil filter change is barely noticeable over a regular start. 

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Drain back is because of the change in the drain back valve in the filter I'm pretty sure it changed since the original design back in the 2nd Gen. Fleetguard filter use to hold full filter then it changed a few years back I started to notice the half filled filters as well.

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I am fairly certain there isn't a drain back valve in the filters I've ran, which explains the drain back. It's not such a big deal on vertically mounted filters. 

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8 hours ago, 015point9 said:

Well seasoned school bus mechanic tells me when they get somebody new changing oil it's only about 2 weeks till they stop filling up new filter with oil before threading on new filter without prefilling.  Interesting part to me was no failures that he knows of.  I fill mine but wondering if really necessary. Other than manual says so.  

Do you prefill?

I refuse to pre-fill oil filters also just because anything put through the center threaded hole is unfiltered.  I won't pre-fill the final fuel filter for the same reasons.

 

I don't even like doing an oil change and fuel filter change at the same time because loss of fuel prime on most diesel engines that are not equipped with an electric lift pump will have hard starts after fuel filter changes. A hard start with zero oil pressure will spin the bearings, Detroit and Mercedes engines are the worst for hard starts after fuel filter changes and will spin bearings when cranking with no oil pressure.

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Its sure interesting reading about these different ways. Lots of things I never thought of.:think:

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1 hour ago, KATOOM said:

I will ALWAYS pre-fill an oil filter if possible.  Been doing this for decades and will continue to do so too.  The whole "you can pour something into the filter by accident and it will get into the oil system" is so implausible that it would be the last thing on my mind.  If I'm that slight of mind of whats coming out the new oil bottle then I'd be pouring the same crap into the valve cover fill hole...

 

I take it you’ve never seen a virgin oil report on particulate size?

 

Oil out of the bottle has more larger contaminates than oil at the end of its life. Oil manufacturers are counting on the oil filter to clean their oil. Any oil that goes thru the block without filtering is doing more damage than good.

 

When you pour oil into the valve cover it drains jnto the pan. The oil added will never go thru anything with a tight tolerance without being filtered. The same cannot be said for oil added to the center of a filter. 

 

1 hour ago, KATOOM said:

 

Why I do this?  Well because I prefer not to shove 70 psi of cold oil through a dry filter element.  Thats simply asking for the media to tear...  Would you know if the media is torn, basically turning the filter into a bypass?  Probably not.

 

Pressure is a measure of resistance, and a dry or wet filter will have the same resistance based on what’s after the filter. A filter rated for 20+ GPM is not going to have an issue with a “dry start”. If it did it would have shown up on my UOA’s by now. 

 

If a filter cannot handle the initial low flow of oil at idle how can it be expected to withstand the psid of normal use and high rpms/flow? Or the resistance created by oil that’s only a few degrees above its pour point? 

 

1 hour ago, KATOOM said:

 

And because I prefer not to hear 5 seconds of dry valve train while the oil system is filling the filter before maximum pressure is achieved.  Especially on engines that are preset to ramp the throttle up upon startup.  Sounds painful.

 

If you’re getting 5 seconds of dry valve train sound you need a new oil! Even with a dry filter and a change I’ve never heard 5 seconds of dry valve train. 

 

My motor is noisier after 6 weeks of sitting than it ever is after an oil change with a dry filter and even then it’s not more than 1-2 seconds. 

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Still something I like about this place is differing opinions with out having to fire off 4 30 round clips of Ak ammo to make a point. I can see both sides here. Though I do remember a member posting a picture of some crud sitting in the bottom of a new one gallon jug of oil. I have been looking ever since and not seen that personally. Clack clack, the AK racks. 

Edited by dripley
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The man I learned from had been filling them for 50+ years. I have been pre-filling oil filters on every vehicle I have owned or worked on for the last 49 years. Not once was there ever a problem caused by this procedure. I know for sure better protection of Cams and lifters in the older engines. If you are working in an environment that causes concern about filling the filter, take care of it and get the job done. I don't like a lack of oil psi issue until the filter fills.

Nothing in that new jug of oil going to hurt anything., unless you put a piece of foil or plastic in there.

a paint filter works well as a pre-filter before the oil filter if need be. we were on a really windy job once and had a concern about the stuff flying in the air. so a paint filter works, but slowly. A clean t-shirt also works.

 

16 hours ago, Mopar1973Man said:

I won't do it. Anything poured in the center hole debris wise is straight to the bearings and oil jets. You would have to hold your thumb over the center hole and fill from the outer. 

What is going to get poured into the filter other than clean oil?

Edited by TryNto
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7 hours ago, dripley said:

Still something I like about this place is differing opinions with out having to fire off 4 30 round clips of Ak ammo to make a point. 

 

Thats because everyone knows they'll get pecked to death around here if they do.

Edited by JAG1
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4 hours ago, TryNto said:

What is going to get poured into the filter other than clean oil?

 

That's just it... virgin oil is not clean. It's going to be the dirtiest oil to go thru the engine for the entire OCI, assuming the filter never goes into bypass. 

 

I'll have to see if I can find the report on how dirty virgin oil is. It's been a few years, but it's what made me switch to not pre-filling filters. 

 

 

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25 minutes ago, AH64ID said:

 

That's just it... virgin oil is not clean. It's going to be the dirtiest oil to go thru the engine for the entire OCI, assuming the filter never goes into bypass. 

 

I'll have to see if I can find the report on how dirty virgin oil is. It's been a few years, but it's what made me switch to not pre-filling filters. 

 

 

 

What about engine without an oil filter like small engines like lawn mowers and log splitters? If its so dirty these engines should fall apart instantly being the oil is dirty right out of the bottle and there is no filter. :think:

 

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2 minutes ago, Mopar1973Man said:

 

 

What about engine without an oil filter like small engines like lawn mowers and log splitters? If its so dirty these engines should fall apart instantly being the oil is dirty right out of the bottle and there is no filter. :think:

 

 

You're trying to compare the tolerances of a small engine to a automotive/industrial engine? Small engines are designed around not having a filter, your 5.9 is not. 

 

That's like asking how air cooled motors can survive without coolant :doh:

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Isn't oil is engineered to keep the internal parts of your engine lubricated during cold starts and dry filters when they are changed?These are short time frames while the engine is starting, or filling up the empty filter.  The small film of oil left on internal engine parts does not drip off bearings, out of spray tubes, nor internal oil passages. The oil remains in several areas including the galleries, and the oil gear-pump. I'd go dry and not worry about it. If you want, yes go ahead and pre-fill the filter. Just know that if anything drops in there, not good. If you are not careful a tiny piece of the silver foil seal on the jug could drop in there. Or small plastic little pieces of plastic from the oil jug manufacturing process. This could destroy your engine if if gets into a oil gallery or spray tube in your engine.

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13 minutes ago, keithb7 said:

Isn't oil is engineered to keep the internal parts of your engine lubricated during cold starts and dry filters when they are changed?These are short time frames while the engine is starting, or filling up the empty filter.  The small film of oil left on internal engine parts does not drip off bearings, out of spray tubes, nor internal oil passages. The oil remains in several areas including the galleries, and the oil gear-pump. I'd go dry and not worry about it. If you want, yes go ahead and pre-fill the filter. Just know that if anything drops in there, not good. If you are not careful a tiny piece of the silver foil seal on the jug could drop in there. Or small plastic little pieces of plastic from the oil jug manufacturing process. This could destroy your engine if if gets into a oil gallery or spray tube in your engine.

 

It very much is designed to stay on the surfaces of bearings, gears, etc. If it didn't the engines wouldn't last nearly as long. 

 

 

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I think about sudden oil pressure against the filter element with an empty filter. If you pre fill a filter, at least it has some buffer or support not blowing out with oil on both sides of the element. I don't know if this is a valid thought. I did loose about 7 qts of oil in a matter of seconds on the driveway when I unknowingly tightened the oil filter against one extra filter gasket stuck to the filter base.

Edited by JAG1

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6 minutes ago, JAG1 said:

I think about sudden oil pressure against the filter element with an empty filter. 

 

But is that really any different than any start after sitting overnight where the filter is already only ±1/2 full? 

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