Pre-charging filters - How important?

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This prefilling nonsense is a joke. Unless your oil change takes several weeks :eek: there is always a film of oil left in an engine. People already spoke of different accidents causing an engine to run without oil for minutes. So an engine is never 100% dry regardless of what you do or don't do to the new filter.

When you start an engine after an oil change I sure hope there is no load on it, right? So an engine without load cannot possibly cause much damage to any part just because oil film is little bit thinner than usual.

What difference does it make if you do prefill anyway? Does it make the new oil start flowing what, 1 second sooner, 2, 3, 4,....???? What exactly is the difference? If prefilling only causes new oil flow delay to be 1 second less then it is clearly not worth the trouble.

As a final reality check, keep in mind that more important than filter being empty of full is viscosity at startup.
higher viscosity = slow oil flow = takes longer for oil to reach engine parts

Consider your typical oil change is done during a nice day, say 70ish degrees, sunny, etc. A typical 5W30 at 40C is 60ish cSt, so already your new oil is around 100 cSt. It should flow farily nice and fast I am guessing.

Now consider my Mazda this morning already full of old oil and presumably a full oil filter at -20C. Using say Shell's 5W30 CCS 5446 cSt @ -30C, so I will guess it was around 4K cSt at -20 this morning (actually I use a different oil but have this spec handy at moment) So my oil despite full oil filter has to force its way throughout engine at 4,000 cSt!!!!!! That is 40X viscosity of your average oil change on a nice day!!!

My guess is that my startup on a cold winter morning is far worse, far more damaging then not prefilling a filter!!!! And you don't want to ask people west of me (western Canada) about their -30 and -40C weather!!!! Still their engine somehow survivie.

So I hope this prefilling waste of time [censored] discussion stops at last. Even the good old M1 vs Syntec fights were more entertaining that this s....
 
Originally Posted By: bob_ninja
This prefilling nonsense is a joke. [...]

So I hope this prefilling waste of time [censored] discussion stops at last. Even the good old M1 vs Syntec fights were more entertaining that this s....



Gee, Bob, sorry... if I'd known we had the world's foremost authority among us I wouldn't have wasted time posting.
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Originally Posted By: bob_ninja
This prefilling nonsense is a joke. Unless your oil change takes several weeks :eek: there is always a film of oil left in an engine. People already spoke of different accidents causing an engine to run without oil for minutes. So an engine is never 100% dry regardless of what you do or don't do to the new filter.

When you start an engine after an oil change I sure hope there is no load on it, right? So an engine without load cannot possibly cause much damage to any part just because oil film is little bit thinner than usual.

What difference does it make if you do prefill anyway? Does it make the new oil start flowing what, 1 second sooner, 2, 3, 4,....???? What exactly is the difference? If prefilling only causes new oil flow delay to be 1 second less then it is clearly not worth the trouble.

As a final reality check, keep in mind that more important than filter being empty of full is viscosity at startup.
higher viscosity = slow oil flow = takes longer for oil to reach engine parts

Consider your typical oil change is done during a nice day, say 70ish degrees, sunny, etc. A typical 5W30 at 40C is 60ish cSt, so already your new oil is around 100 cSt. It should flow farily nice and fast I am guessing.

Now consider my Mazda this morning already full of old oil and presumably a full oil filter at -20C. Using say Shell's 5W30 CCS 5446 cSt @ -30C, so I will guess it was around 4K cSt at -20 this morning (actually I use a different oil but have this spec handy at moment) So my oil despite full oil filter has to force its way throughout engine at 4,000 cSt!!!!!! That is 40X viscosity of your average oil change on a nice day!!!

My guess is that my startup on a cold winter morning is far worse, far more damaging then not prefilling a filter!!!! And you don't want to ask people west of me (western Canada) about their -30 and -40C weather!!!! Still their engine somehow survivie.

So I hope this prefilling waste of time [censored] discussion stops at last. Even the good old M1 vs Syntec fights were more entertaining that this s....



Lots of assumptions...

There is load on the motor any time it's running. Do you honestly think you can compare a running motor to one that's being turned by the starter? Why is it then that it doesn't knock until it fires up?

I don't know about your cars but one of mine only knocks if I don't prefill the filter. I would prefer to not hear it knock so I take 5 seconds out of my busy day to prefill.

The other car doesn't knock but the oil light takes a few seconds to go off if I don't prefill instead of going off before I release the key. I would rather have pressure before the engine fires.

Maybe you should keep your valuable data to yourself or companies like Preluber will be going out of business.
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What about engines with the filter mounted horizontal or upside down threads down?. I fill the filters that can be filled. Threads up.
 
Originally Posted By: LexusAussie
Where's the harm? If it cuts a second or two from the time it takes the fresh oil to fully circulate that has to be a good thing. It only takes a few seconds to add this step.


All mine are horizontal so don't see how I can put much oil into it without spilling.
 
Buick,

The load is minimal, certainly insiginificant compared to actual driving.

I never had this "knock" on my machines, including a motorcycle and lawn tractor. Others wrote about having different causes, such as cold mornings, etc. (don't remember all the cases)
I don't remember anyone actually showing a damaged engine or a significant amount of wear/damage from knocking.

I guess if a filter is mounted in such a way that you can easily install a full filter then sure there is no harm. However, these days I would think such engine configuration would be rare.

I see many new cars have very small engine compartments and very compact engines. All mine (Honda, Mazda, Kawi bike) are mounted horizontally so I would spill most of prefill oil. I would imagine that for most engines it is difficult to access oil filter.

Maybe it is different for different types/brands.
 
The last couple of times I did oil changes, I filled the filter - thus soaking the media - then turned it upside-down to drain it into my wife's short, wide diameter 32 oz plastic measuring cup that I permanently stole from her kitchen.
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I may do it all the time now. The last time I did it, there was small slivers of metal that entered the measuring cup. I discarded that oil afterwards. So if using this method, either buy a quart of cheap dino for oil discarding during your next 2-3 oil changes -- or filter out the metal shavings and reuse the measuring cup oil afterwards.

Neither vehicle makes noise on startups after oil changes -- so I didn't hear any difference at startup using this soaking method.
 
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I've pre-filled filters that were mounted horizontally.
Left a small air space in the filter before 'carefully' placing filter on threaded tube and spin on. A drop or two may fall out, but not much.
I've also filled a filter, then held it at the angle the filter would site at, pouring out some back into the bottle (funnel).
While not FULL, the filter was about 1/3 filled with oil; still helped.
 
I've prefilled filters since 1970. In the case of filters mounted horizontaly-I pour enough oil inthe filter to bring it to the top once. By the time I'm ready to install the filter all of the oil has been absorbed by the media. Never has any start up rattle on anything I've owned
 
I never really did it until I read about it on here. Now I do it on my corolla as it is almost vertical so I can fill it almost completely full
 
I never pre-soak an oil filter because 3 of the 4 vehicles I change are horizontal mounts and I make enough mess taking the filters off..but none of my vehicles "rattle" on start because I change the oil hot not warm. Plus I use PP which really pumps fast even in the Winter.
 
A foreign car mechanic told me years ago, to always fill the oil filter before installing. He even demonstrated how to do it when horizontally mounted, just with a bit less oil as the media absorbs quite a bit. He claimed that in his shop's experience, quite a few cars develop noise due to repeated dry starts.
 
On my Jeep, I have a button that I wired in that engages the starter whether the key is inserted or not. Without the key of course it won't start, but crank forever.

I did this because the neutral start switch is bad, and I don't want to spend $300 to replace it, and this is a work around. On the other hand, it works great to prefill oil filters. If you didn't want to go so far as to install a special button, you can get one of those mechanics remote starters, with aligator clips that attaches to your starter solenoid. With that you can crank your engine over without starting it.
 
My oil filter is nearly horizontal.

Fill it to about 2/3 full then quickly placing it in position and spin it on I hardly lose a drop.

Removing the filter reverse the process. Loosen and unwind oil filter about 1/4" back from the engine base. Let it drain until it stops dripping. Remove the filter from the engine and place it in an upright position. Check how much oil is left in the filter.

Now you have established your benchmark on how much oil you can fill the filter to, before you lose a drop or so on reinstallation of the oil filter.

To those who think its a waste of time, I can think of at least a dozen other ways ways (to vegetate and excel) in the art of time wasting.
 
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