Pre-fill Oil Filter?

[Svashtar]

So, for a few years in the '70's and '80's in my teens and early 20's I worked in a garage with ASE Certified mechanics who handled tune ups and more advanced work, and did misc "joe jobs": O/F changes, tires, batteries, fan belts, hoses, coolant flushes, alignments, wheel bearing repacks, etc. In at least 10,000 oil changes, mostly with bottom mounted oil filters where it would have been easy to do, we never once "pre-filled" the filter, and until the other day I had never even heard it mentioned as something to do. I just changed my oil for the 22nd time the other day, and was screwing in the new filter and my neighbor told me I was "ruining my engine" by not pre-filling the filter. I asked him how I was supposed to fill it up and get it onto the engine without spilling new 5-20 full synthetic all over the side of the block, and he said some was going to spill but it was necessary to have some in the filter so the OP didn't fall too low and the engine had lube.

I do the routine when I take off the O/F, tilting it back to minimize spillage, then move it to the front of the car, then get under to pull it down onto the drain pan. Reverse operation with the new. I suppose I could get some oil into the new filter first, but have never bothered. I have 6 quarts of always full synthetic and don't want to waste any.

Anyone else add oil to the filter before installing? I know that our DOHC engines hold a lot of oil in the top of the engines, and count on any residue up there to work in the couple of second it takes for the O/F to fill and the oil pressure to max out.

[Joe Walsh]

I just saw a test where they showed that it takes multiple seconds after start up for the newly installed oil filter to fill with oil, while the engine sees NO oil pressure.
In the long run it's not a great scenario for main bearings.
I've always completely prefilled my oil filters on any engine with a vertically positioned oil filter.
On 'angled' oil filters, I normally partially fill them to avoid dumping fresh oil all over the place while spinning the filter on.

LINKY >> https://www.youtube.com/watch?v=939WTeorBnQ



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[Svashtar]

Thanks, I watched that same video. I can’t imagine it takes too long to cycle the oil and build up pressure, but I understand the point. I’ll try and add a little next time I guess, as long as I can get it screwed back onto the block without spilling it, which I kind of doubt.

I know some mfrs recommend not pre-filling for a specific reason, but that doesn’t apply to our cars as far as I know. I had somehow never heard of the practice.

By the way, I don’t want to start a new thread, especially a dreaded oil one, but I’ve always only used regular full synthetic 5w-20. I’m wondering now that the car is at 125,000 if I should switch to the “high mileage” formula? Supposed to be anything over 75k, but I’ve never bothered, and might be missing a bet.

(Just checked one source and it says that the oil formulas from std to high mileage are identical, except high mileage adds a “seal conditioner” that can help protect seals from degrading, causing oil loss. Makes sense, and guess I should have switched 40-50K ago.)

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[crouse]

I've always pre-filled my oil filters and almost all of my vehicles except for my Marauder had bottom mounted oil filters.

For my Marauder, I'll fill it full then let it sit as the oil soaks into the filter element. I usually add a little more oil then install it. Little to no oil spills as I install it.

[crouse]

Also, I think the High Mileage oils have additives that make seals swell up a little to help seal leaks.

[massacre]

I always pre-fill

[Svashtar]

I've always pre-filled my oil filters and almost all of my vehicles except for my Marauder had bottom mounted oil filters.

For my Marauder, I'll fill it full then let it sit as the oil soaks into the filter element. I usually add a little more oil then install it. Little to no oil spills as I install it.

Well, then I feel like an idiot for not knowing about it, especially after doing LOF’s in a shop for years. I’ll try it next time, letting it soak in like you say.


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[Svashtar]

I always pre-fill

Thanks!


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[FordNut]

I never do it. 370k miles says it's probably not necessary.
I do use Mobil1 full synthetic.

[Svashtar]

I never do it. 370k miles says it's probably not necessary.
I do use Mobil1 full synthetic.

Me too, never had anything but full synthetic and Motorcraft or K&N filters in it for 22 oil changes now. (I saw a great review on it though and think I’ll try a Mobil 1 extended filter next time, pretty impressive.) And I’m going to switch to the high mileage oil as well then, which will be at 130K miles. Has the exact same formula as the regular stuff, with some seal conditioner added.


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[fastblackmerc]

No need to prefill. Hold the go pedal to the floor while cranking the engine for about 15-20 seconds. With the pedal to the floor car won't start.

[Svashtar]

No need to prefill. Hold the go pedal to the floor while cranking the engine for about 15-20 seconds. With the pedal to the floor car won't start.

Great idea! I didn’t know that about the pedal preventing the car from starting. Thanks for the tip.


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