Pre-filling filters effect on first startup

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Spin-on filter in my car installs straight up, so I can fill it all the way before I screw it on. Only the galleries need to purge before oil pressure can build. Since I just installed an electronic oil pressure gauge that updates a few times per second, I decided to record what the pressure does on the first startup at my most recent oil change. I used 10w-30 Valvoline Full Synthetic with Maxlife Technology and a Mann W917 filter.



It will be a while before my next oil change, but when that happens I'll do an experiment. I'll use the same oil and filter, but this time I will only put a splash of oil in the filter instead of filling it to the brim with about 1/2 quart. Be interesting to see how much longer it takes to build pressure.
 
If the filter was bone dry, it will probably take 4~5 seconds instead of 2 second to reach full pressure.
 
While I don't think adding oil to the new filter is absolutely necessary...I can't see any downside....I've done it for years...and will continue to...
 
Awesome! This topic has been
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many many times over the years; finally some science to definitively answer the question!

When you post up the next video please make sure to link to this one.

Question for you: any plans to test a 0w30 vs the 10w30? It would I suppose need to be at the same outside temperature but that has been debated here also [insert positive displacement pump discussion here]
 
I have timed it on my truck.

FL-820S size (Same size as PH-2, XG2, or PH-16) takes exactly two seconds longer when dry.

I only did it once, for the value of the experiment. It was a warm engine that hadn't been shut off for long.
 
Originally Posted By: JLTD
[insert positive displacement pump discussion here]


Oil viscosity shouldn't really matter with a healthy PD pump.
 
No real difference, the oil filter takes in my cars maybe 2 seconds to fill up when you start it after a change, and i can't do it in my cars anyway, in one it's horizontal and on the other in fact at a 45 downward angle!
In fact, Ferrari Colombo V12s have two oil filters and they are both directly pointed downward! and they don't blow up after an oil change do they.
 
As far as I know, the only way to insure high oil pressure at startup is with an oil accumulator (Moroso, etc). It pressurizes the oil system *before* startup.

I don't know if it's necessary; there should be enough residual oil at bearing points for almost no wear for startup and low RPM operation for brief periods. Engine starts do wear more than pressurized operation, but it's low enough that motors last ... well, as long as they last. Maybe an option if you are looking to keep the vehicle forever and are looking to extend engine life beyond, say, 200,000 mi.
 
Originally Posted By: Johnny2Bad
... there should be enough residual oil at bearing points for almost no wear for startup and low RPM operation for brief periods.


Yep ... if these engines in the video link below can run for 10+ minutes with no oil before blowing up, I'd think the residual oil will protect everything for 5 sec or less of running before oil pressure is established.

https://youtu.be/x3CfLBkew2c?t=7m18s
 
I prefill 'where practicable'. That said, I realize it's more of a 'feel good' practice then something that will have a significant effect on engine wear. Look at how many shops, dealers, indies, and quick lubes that never prefill.

And there's been some posts here in the past about how new unused oil actually has more harmful particles in it then used oil and one should change the filter some time after the OC. Not something I'll ever do no matter the science behind it, but much like prefilling, strokes for folks.

And yes subject has been beaten to death, but so have many topics here.
 
Sis had a 1988 Jeep Cherokee w/ 4.0 I6. 'Twas said the cam and crank pos. sensors BOTH needed to "go through their zeros" for the engine to fire up.
That required 2.5 - 3 seconds whether ice cold or warmed up.

I always thought the engine benefitted from that low rpm cranking as the oil pumped up.

This is separate from the "pre-filling question".
 
Originally Posted By: Sayjac
I prefill 'where practicable'. That said, I realize it's more of a 'feel good' practice then something that will have a significant effect on engine wear. Look at how many shops, dealers, indies, and quick lubes that never prefill.

And there's been some posts here in the past about how new unused oil actually has more harmful particles in it then used oil and one should change the filter some time after the OC. Not something I'll ever do no matter the science behind it, but much like prefilling, strokes for folks.

And yes subject has been beaten to death, but so have many topics here.

Basically what I was going to say.

I disagree with the naysayers about the new oil can cause harm. Look at VOA's, insolubles are minimal, lower than or equal to UOA's. Plus the new oil is poured into the top half of the engine, where it would do "damage" to the top end.

And if you have a horizontal mount filter, you can still add some oil too it. I can add about 1/3 a qt to the FL820s size filters on my F150. I just add it and it gets absorbed by the media. Spin it on quickly enough and nothing comes out.

But as said, it just makes me feel good, and if I forget to do it, I don't worry about it.
 
I would think 2 seconds to fill a filter when empty would be a max. I replaced an oil line to a remote filter on my 5.4 F-150 and had a problem with how it was seated to the engine block. I started the engine and shut it off after about 5 seconds once I realized I had a problem. In that time it pumped almost all the oil out of the engine. I never realized they moved that much oil in that small of a time.
 
Originally Posted By: ZeeOSix
Originally Posted By: JLTD
[insert positive displacement pump discussion here]


Oil viscosity shouldn't really matter with a healthy PD pump.


"shouldn't" ...leaves a "?"... I am requesting this as real world data....
 
Back in the day, my 98 Camry v6 would have a lot of noise if started with a dry oil filter. Although the filter is at an angle, I'm still able to soak the media fully, drain the excess oil out and spin it on without anything spilling on the block. Engine chatter is greatly minimized and oil light goes off instantly within a second.

I'm sure that engine chatter and clunking is fine on the thin coat of oil around said parts but if I can minimize the startup noise by even soaking the filter media and cut down on the second or two or restricted oil flow, WHY NOT DO IT?!?! Over 10, 15, 20+ years and 50+ oil changes, it will add up to excess wear I imagine, even if it's a small amount.

Original engine is still running at 315,000 miles and this is the famous SLUGE monster engine.



I always fully fill my oil filters to the brim and spin them on. Barely any engine chatter and oil lights go out instantly like I didn't even do an oil change. I like it this way. Yes it's Anal to some, but its an oil change practice worthy of a trophy.
 
I can't for the life of me figure out why anyone that knows about cars and does their own work wouldn't pre-fill the filter if the position of the filter on the engine allows doing so.
 
Originally Posted By: demarpaint
I can't for the life of me figure out why anyone that knows about cars and does their own work wouldn't pre-fill the filter if the position of the filter on the engine allows doing so.

Maybe because your engine will last just as long if you don't?
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