Pre Fill Oil Filters?

[Byron Gudmestad]

Hate to start an argument on my first post, I always pre fill (charge) my oil filters. Don’t care if it horizontal or vertical and I may spill some oil, it gets better with practice.

My justification is removing old filter drains all oil in the channel above it, so just putting in a new filter creates a huge air embolism. With the oil filter removed I don’t know if oil drains out of the pump as well, suspect it does.

My research indicates when starting a car the engine is cranking between 200 and 500 rpm and this is with absolutely no oil pressure, until oil can be sucked from the level of the oil in the pan, up to the pump itself, into and filling the filter, then finally up the galley and out to the distribution channels. Pushing that column of air from the filter and empty chambers ahead of it, all at between 200 and 500 RPM at 0 PSI.

I pre charge my filter, by repeatedly topping off until it draws down no more, start before draining my old oil and continue until I am done with the change and install the charged filter.

I realize some air is in there, but much less than a dry filter. I had always been told that most engine wear is caused when starting the engine, due to no/lo oil pressure. Can this all be wrong and starting a car on a dry filter can be justified as some would suggest?

Topic

[twiggy]

I do the same thing for the same reasons you outlined. Am interested in seeing what others have to say here too.

[Josh]

I personally don’t think it’s much of an issue. Unless the engine is brand spanken new and has absolutely no oil in any part of the engine, it’s ok to install a dry filter. Your engine already has a vary thin coat of oil around the moving parts so I don’t really see a point in it. During a normal oil change, you don’t drain 100% of the old oil. Some of it is still with in the system.

That’s just me though.

[mckrishes]

I used to change my oil filter without putting any oil in it. Then I watched Eric’s oil change video and he said he puts some oil in the filter before installing. I started doing the same thing. Not sure if it makes a difference and it’s messy for me because my filter is horizontal.

[skim3544]

I work on BMW and Mercedes and they have canister filter that only the filter element pops out. Any oil in the filter housing drains completely out as soon as the center rod gets removed. The center rod is usually part of the oil canister cap so there is no good way to fill the canister without making completely mess. Seeing these engines last well over 300K without using synthetic oil I don’t think this is an issue.

But if you want to do it, go for it. I don’t think it is hurting the engine as long as clean engine oil is used.

[LJ11194]

I always put oil in my filter, even on my lawn tractor. It’s just the way I was taught to do it and I never saw any advantage to not doing it that outweighed the potential risks.

[chevyaz]

i have been pre filling my filters for years just for that reason.

[Craigo]

I know of people who just put oil on the gasket and make sure the oil get a good warm up after it’s filled, but personally i always pre-fill my oil filter, i don’t understand why you wouldn’t it just seems like a preventative measure in getting the oil into the rest of the engine without the chance of shearing on parts.

[W00DBar0n]

Coming from a hydraulic tech its pro vs cons are so insignifican on a automotive hydraulic lube system, that there is no real need to. Its not some of the systems out there where pre-filling and bleeding is need or major damage will ensue. If you are worried about air and all that in the systems move the oil pick up tube and pump below the oil pan because those two area drain out due to the law of gravity.
Sorry for the rant but i grew up with a hydraulic tech for a dad so i grew up with hydraulics.

[dollman0]

This comes down to boundary lubrication waiting for the hydrodynamic oil pressure to occur. There are people who swear the dry start is an issue but it is no longer a concern with modern oils. The study guide I used for the A9 exam states that pre-filling oil filters is no longer necessary. However, a Volvo D12 engine will set codes if it is run too long without oil pressure.

Most oil filters leak down on a hot engine allowing 1/2 of the oil to drain back, even with the rubber valve in the oil filter. Just take one off a cold engine sometime, you will see it is nearly empty.

If you feel more secure by pouring the filter half full of oil and soaking the paper, its your time wasted and not mine. I am neutral on this subject but time is money

[Steffen Nyegaard]

A mechanical engineer told me that the wear from not pre-filling the filters equates to 5-700miles of driving wear on the cylinder surface. He explained it as because there is no oil pressure the cylinders are being pressure blown free of oil film quickly.

Seeing how much you can pour into a filter (usually takes 3 times while letting it digest each gulp) I can’t see it as being a bad idea to not pre-soak the filter medium before putting it on there. There is a reason filters have anti-drainback valves?

As a question, is there any way a empty filter could cause foaming for the first few minutes until it is soaked all the way through and not releasing air anymore. As it is not a on off swift I would imagine the filter leaking air out while filling over the first minutes of running, similar to that of water conserving inlays for your fosset?

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