Pre-fill OF

[dnewton3]

There's a huge difference between added wear and blown-up/failed engines. People use the same arguement when talking about engine wear related to oil cleanliness from filtration or from the oil viscosity used. More engine wear over the long run typically won't result in engine failure, but a more worn engine can effect the overall mechanical condition and performance of the engine.

There is no data set that would prove the wear issue one way or another, relative to pre-filling the filter. It's theory at this point.
I cannot prove that pre-filling doesn't reduce wear, any more than you can prove it does.
The data just doesn't exist.

Also, the wear issue relative to filtration is not a universally applied concept.
Reducing particulate is a very good idea; it's important.
But at some point there is a law of diminishing returns, relative to the OCI duration. "Normal" OCIs don't really benefit from hyper-clean oil; that data IS present and available for all to see (if they are willing to see it with an open mind). Once oil is "clean enough", then making it "more clean" doesn't return a wear reduction worthy of the ROI. As you and I have discussed, the difference between a 95% filter and a 99% filter (at 20um) isn't going to make any appreciable difference in wear in a 5-7k mile OCI. There is so much other noise (variation) in "normal" wear rates that you cannot find a statistically significant difference in the wear data relative to the filter efficiency.

 

[ZeeOSix]

As you and I have discussed, the difference between a 95% filter and a 99% filter (at 20um) isn't going to make any appreciable difference in wear in a 5-7k mile OCI. There is so much other noise (variation) in "normal" wear rates that you cannot find a statistically significant difference in the wear data relative to the filter efficiency.

Like I've mentioned in similar discussions, I'm not talking about 95% @ 20u vs 99% @ 20u filters. Of course there isn't enough difference between those two efficiencies to measure any short term wear impact difference. But when comparing 50% @ 20u or 95-99% @ 40u filters to 99% @ 20u filters, there can be an ISO code or two difference in oil particle count cleanliness which would make more difference in wear from particulate. It's just not a fact when someone claims (not you, but others) that oil filter efficiency makes no different in engine wear.

 

[64bawagon]

The small effort required to pour clean oil from a clean container into a clean filter reduces a few seconds of zero oil pressure is an easy trade for me. A few seconds multiplied by 2 oil changes a year multiplied by years starts to add up.
I do however think that clean shop practices likely yields more benefit but thats another dataless rabbit hole

 

[goingplacesanddoingstuff]

Always.

 

[dnewton3]

Like I've mentioned in similar discussions, I'm not talking about 95% @ 20u vs 99% @ 20u filters. Of course there isn't enough difference between those two efficiencies to measure any short term wear impact difference. But when comparing 50% @ 20u or 95-99% @ 40u filters to 99% @ 20u filters, there can be an ISO code or two difference in oil particle count cleanliness which would make more difference in wear from particulate. It's just not a fact when someone claims (not you, but others) that oil filter efficiency makes no different in engine wear.

I agree with you totally in this regard. Large disparities in filter efficiency of two products will most certainly make a difference in wear rates! Oil filter efficiency is important to a very large degree. It's just not infinitely important; there's a law of diminishing returns at the high end of filtration.

 

[atlex]

Data is support of pre-fill

Going on speed to pressurise the system alone.. it's on the nail. Thanks for sharing. I always prefill my new filter enough that it it won't spill when I install it - this is like 65% full or so - most of my filters are side mount!

 

[ARCOgraphite]

I think that the bearing striations are due to particulate moving through the journal whilst the system is pressurised, not "dry" starting - which is never dry. The crank pins are near mirror polished.

I will state again, some engines can loose their pump prime, and a totally filled filter canister would work as an impediment or obstruction rather than being a benefit in such a case. So I propose to leave a bit of air space in the filter, around 1cm from the base or adbv.

Now, argue the MUCH greater importance of a base-end bypass vs. Dome -end with regard to engine wear.

 

[ZeeOSix]

I think that the bearing striations are due to particulate moving through the journal whilst the system is pressurised, not "dry" starting - which is never dry. The crank pins are near mirror polished.

During engine cranking by the starter, there is basically zero oil film thickness in the bearings because there isn't much rotational speed to build an oil wedge (the MOFT) inside a journal bearing.

I will state again, some engines can loose their pump prime, and a totally filled filter canister would work as an impediment or obstruction rather than being a benefit in such a case. So I propose to leave a bit of air space in the filter, around 1cm from the base or adbv.

Pumps that don't prime themselves are typically ill designed and/or in bad health and have too much internal clearance, and don't produce much suction at low RPM. Oil pumps designed well and in good health will pump air and easily self prime with oil because there will be a good level of vacuum on the inlet side when the pump is turning. Never heard of any engine's pump not priming after an oil change because the oil filter was pre-filled fully or to some other degree. I've completely rebuilt engines, and the oil pump has always self primed on initial startup as long as the pump pickup tube was covered by oil in the sump.

Now, argue the MUCH greater importance of a base-end bypass vs. Dome -end with regard to engine wear.

If the location of the filter bypass valve was that critical, then more than only a few filters on the market would have a base end bypass valve. And it would also matter depending on how the filter is orientated when mounted. For instance, I would not want a base end bypass on a filter mounted vertical with base down (a dome end bypass better in this case), but I would if it was vertical with base up.

 

[ZeeOSix]

The bigger the oil filter (like giant ones on Caterpillars and similar engines), pre-filling would help more than on a very small filter. It's all about how much time it takes to build full oil pressure. How much time is too much time? If nobody can say, then it's best to try and make that time as small as possible.

 

[SubieRubyRoo]

The small effort required to pour clean oil from a clean container into a clean filter reduces a few seconds of zero oil pressure is an easy trade for me. A few seconds multiplied by 2 oil changes a year multiplied by years starts to add up.
I do however think that clean shop practices likely yields more benefit but thats another dataless rabbit hole

When looking at at least Subaru oil pumps and especially with “normal” filter sizes, once the crank is spinning it’s pumping significantly more volume than the canister can hold… I.e., likely before the engine even fires and begins to run, the filter itself is full. If you’re that worried about it, hold the pedal to the floor for 2-3 seconds so that no fuel is supplied, then let off and let it fire.

It’s not like when one drains the oil that all surfaces are wiped clean from residual oil… and this is why I’m in dnewton3’s corner. Even if the data existed, you’d need so many samples and such a long test duration, that for any normal vehicle lifetime there is statistically zero difference between pre-fill or dry.

I used to prefill, but now I look at pre-filling filters like Linus’s safety blanket… it gives comfort to the user, but no objective benefit. If you do it, congrats; if you don’t, there’s no negative consequences.

 

[64bawagon]

Zero cost to pre-fill and the reduction of zero oil pressure time is enough for me. Maybe it helps, maybe it doesnt, but in the grand scheme of things theres people spending a lot of time on things of much more dubious benefit and none of us will never know for sure.

BYW, I still root for Linus to meet the great pumpkin every year.

 

[ARCOgraphite]

During engine cranking by the starter, there is basically zero oil film thickness in the bearings because there isn't much rotational speed to build an oil wedge (the MOFT) inside a journal bearing. Yes the crank pins are not floated but there is oil in there, and again, the journal surface roughness is finished to a high degree.


Never heard of any engine's pump not priming after an oil change because the oil filter was pre-filled fully or to some other degree. I've completely rebuilt engines, and the oil pump has always self primed on initial startup as long as the pump pickup tube was covered by oil in the sump. Well, I just mentioned it in my past experience, so you have heard of it. I bet many -intentionally or not- are leaving a bit of an air gap when prefilling so it is not an issue. For reference, external from pump Buick V8 are notorious for no priming from a dry start - but this is typically seen after rebuilding and ... I just rebuilt one a couple years ago.

If the location of the filter bypass valve was that critical, then more than only a few filters on the market would have a base end bypass valve. And it would also matter depending on how the filter is orientated when mounted. For instance, I would not want a base end bypass on a filter mounted vertical with base down (a dome end bypass better in this case), but I would if it was vertical with base up. Good point on the orientation, but there is still media washing on a dome end bypass and none of that occurring with the base end relief valving. I will also say the lack of this superior design is a form factor consideration and some of it bean counting

Good response and a good exercise !

In the garage with the torquey 340 Buick (in primer) after laying the crank -

 

[Bailes1992]

I'll just reiterate what I said in another thread about this video.

The host pre-fills his filters and therefore had a massive confirmation bias. The video wasn't to determine if more wear was caused by not prefilling an oil filter. All it did was prove that using a drill (which was probably spinning far slower than the oil pump would have been if the engine was idling) the oil pressure rose faster with a full filter. And so what?

Also found the host annoying and condescending. This test wasn't in any way 'scientific'. Pointless, irrelevant tests to make the host look like he's right.

 

[Sayjac]

Prefill or not, especially in pc applications, to me a matter of personal preference. What 'I' most took from the Speed video is that for those that do prefill (there are many), it dispels/debunks the idea stated by some members that new oil had more particulates/impurities in it than even oil in the engine. And, that amount of unfiltered prefill oil would do immediate damage to the bearings. Quoting @JGmazda this thread, "C'mon now."

 

[DGXR]

We've heard it countless times: most engine wear occurs at startup, when the oil is down in the pan. This would be especially true during an oil service, where some/many of the internal oil galleys and pipes have been emptied (which does not occur in normal everyday use). So, anything that helps build oil pressure faster during an oil service is a positive IMO. I understand that pre-filling my oil filters probably won't make any noticeable difference during the life of my engine, but also it's easy and it's free

 

[Malo83]

I only prefill my two Turbo equipped vehicles, all my vehicles are vertical mounted filters.

 

[SubieRubyRoo]

We've heard it countless times: most engine wear occurs at startup, when the oil is down in the pan. This would be especially true during an oil service, where some/many of the internal oil galleys and pipes have been emptied (which does not occur in normal everyday use). So, anything that helps build oil pressure faster during an oil service is a positive IMO. I understand that pre-filling my oil filters probably won't make any noticeable difference during the life of my engine, but also it's easy and it's free

just because one has heard something countless times doesn’t make it true… I can’t remember who had it but they posted a white paper results on wear, and there was some startup wear, but overall wear is much more dependent on RPM; low RPM regardless of cold or hot engine had lower wear than say 4k+ RPM operation in either temp condition.

It’s kind of a match made in heaven- when oil is cold and thick, tolerances are loose and when temps rise and the oil thins out, the engine has warmed and the tolerances have closed up to their running clearances. There’s obviously always other factors that come into play, but when you pile everything together it’s why most experienced folks on here know that you can easily run 90%+ of ALL gas engines on the road on a 5w40 year round with zero issues.

It’s also why the Mobil 1 FS 0w40 is a go to for so many. It’s robust, has many stringent certifications & approvals, and will easily service any temp from -35*F to 120*F while maintaining adequate MOFT to protect the rotating assembly and sliding contact points.

 

[ZeeOSix]

When looking at at least Subaru oil pumps and especially with “normal” filter sizes, once the crank is spinning it’s pumping significantly more volume than the canister can hold… I.e., likely before the engine even fires and begins to run, the filter itself is full.

I'm looking for the member here that showed a video of a clear oil filter he built. If I recall correctly, in one of his videos he cranked the engine with the clear oil filter dry, and it showed how the filter filled up with oil as the engine cranked. It took a while for the filter to fill up. Engine cranking RPM is going to be way less than fired up RPM, and most engines will fire-up with little cranking. In either case, since it's a positive displacement oil pump, the engine will rotate X revolutions before full oil distribution and pressure is obtained.

 

[4WD]

We've heard it countless times: most engine wear occurs at startup, when the oil is down in the pan. This would be especially true during an oil service, where some/many of the internal oil galleys and pipes have been emptied (which does not occur in normal everyday use). So, anything that helps build oil pressure faster during an oil service is a positive IMO. I understand that pre-filling my oil filters probably won't make any noticeable difference during the life of my engine, but also it's easy and it's free

So, think he also said (sampled both ways) - no significant contamination existed … (one claim made in the past) …

 

[kschachn]

We've heard it countless times: most engine wear occurs at startup, when the oil is down in the pan. This would be especially true during an oil service, where some/many of the internal oil galleys and pipes have been emptied (which does not occur in normal everyday use). So, anything that helps build oil pressure faster during an oil service is a positive IMO. I understand that pre-filling my oil filters probably won't make any noticeable difference during the life of my engine, but also it's easy and it's free

What has been shown here is that the most wear occurs during warmup before the additives are fully functional. At startup the oil is cold and has a high film thickness.

Of course you don't get to the warmup phase without a cold start so you really want to get to normal operating temperature as soon as possible.