Oil filters

when you change your oil filter is it a good idea to fill it up. with oil before you put it on car.i have had several shadetree mechanic that say it do not matter.

In the long run, it may be beneficial to fill the oil filter. There may be 5 second delay on some cars while the oil filter is filled before the oil pressure gets up to normal. It is particularly important if you do not fill the oil filter before installation to stop the engine, let it sit for 5 minutes or so and check the oil level. Some oil filters hold a pint of oil or so and you should bring it up to the proper level.


Ideally, you should fill the new filter before installing it . . . this is called priming

However, that isn’t feasible if the filter is installed horizontally or upside down

On commercial vehicles in which the large filter actually holds several quarts, priming is critical

On most passenger cars, the filter volume is small and they fill very quickly. The engine is usually warm and flooded with oil so the one or two seconds needed to build oil pressure is simply not an issue…If you are going to worry about stuff like this, you can install a pre-lube pump, electrically driven, that provides oil pressure before you ever crank the engine…No more “dry starts”, ever!

For passenger car sized filters, while priming is a good idea, does anyone this forum believe they’ve ever detected a shortened engine life due to never priming?

Good question, Joe. Some of my vehicles have had the horizontal filters described by DB4690 making priming impossible, and I never worn an engine out. Ever. Even after 338,000 miles. Far more important than priming the filter is actually CHANGING the oil and filter routinely and monitoring the oil level between changes.

Having said all that, my current engine has a fillable filter (positioned bottom down), and I always fill it with oil before installation. But I doubt if what I’m doing is meaningful in the real world. It has meaning theoretically, however, so I do it. Can’t hurt.

Here’s a question for those professionals among us - do shops prefill filters?

All of my Toyotas to date have had a horizontally installed oil filter, and they all had a normal life span

Let me be more specific, if I could prime my own oil filter without making a mess, I would


To answer your question

I prime the huge oil filters on large diesel engines

This serves multiple purposes, at least for me

The engine does not have a dry start
After letting it run for awhile and then shutting it off, I check the level again. I almost never have to top off if I’ve primed the filter

I always do but its just a small matter. Just makes me feel better to get the oil pressure up faster.

Priming would cause a mess on both my horizontally-mounted-filters, 20 year old Corolla and, 40 year old Ford truck, so I’ve never primed those in all those years, and have suffered no ill-effects to date. I do what @Trideq recommends, to wait 5-10 minutes after filling the crankcase w/oil, before starting the engine. And only idle rpm until the engine has run 2-3 minutes, at which point I’ll boost the rpm a tad in order to verify there are no leaks from the filter.

Oil changing involves some waiting, if it is done correctly. Wait for the old oil to drain out, and wait for the new oil to fully fill the crankcase. There’s a bunch of stuff the DIY oil-changer can do while waiting though. It’s not wasted time. The car is sitting up in the air, so that’s a good time to inspect the underside for any funky stuff going on. The CV boots. The suspension parts for play. Leaks. Splash guard. Heat shields. Engine and xmission mounts. Front brake pads. And it’s a good time to get the shop vac out and clean the debris from the under-windshield air vents. Prevent that leaf from snaking in and hitting the blower fan and making a racket.

“Here’s a question for those professionals among us - do shops prefill filters?”


On at least half of the cars that come in that’s not possible. Either they’re a cartridge type or not able to be installed with oil in them.

On diesels in pickups, yes, since the filter can hold up to 2 quarts and it can take quite a while to fill it.

If it’s something that’s in for major engine work then yes, or alternately the engine is cranked over until it has oil pressure.

For routine oil changes, no.

It probably doesn’t make much difference and it’s impossible to do on a number of vehicles anyway.
The oil filter on my son’s Camry is almost in a vertical position pointing downward and the one on my Lincoln is canted upwards somewhat but the filter has to go in upside down to squeeze past the power steering pump so filling either one is not an option.

Most of the oil in the filter will bleed out anyway on horizontal or upside down filters.

What I usually do is remove the fuel pump relay or fuse and crank the engine over until the oil light goes out. Does this make any difference? I have no idea but I feel better about it… :slight_smile:

This “professional” made an effort to fill filters before installing them. Small block Chevrolet filters were convenient to fill before installing while Ford Winsor V-8s and most other engines had their filters mounted horizontally or inverted. My compulsion to use filters with check valves allowed partial filling on all but the inverted filters. I can’t say that my compulsion added any significant miles to any engines but reducing the seconds that an engine clattered when first started gave me some personal satisfaction.

Don’t play with fluids unless you like cleaning them off the floor. Concentrate on putting the plug and oil filter on right and watch out for the double gasket trick. Remembering to do all the steps will seem more important than extra work when you fail at it.

Somebody used to remove the plug and walk off the job for an hour to let it drain extra good. His wife got in and drove it down the road to a store with the plug out. Just concentrate on completing the steps and you will have less to worry about overall.

I have tried this on My Camry, '05 with vertical oil filter. If I fill it up (no spills since it is vertical) and then crank the engine, the 1st start is normal and the oil light goes out immediately. If I don’t I have one second of noisy engine and a lag in the light. I did my 1st and 2nd oil changes on my Mazda CX-9 with prefilling the vertical filter and the car didn’t even notice the oil change. This particular filter takes close to half a qt of oil.

My inline-6 engine in my F 150 has the filter mounted sideways, so prefilling is impossible (or at least messy). It also has a reputation for longevity. Mine’s at 152k and counting.

With experience, I’m becoming ever more convinced that oil-change fetishists are barking up the wrong tree: rust, electrical, wrecks…SOMETHING (almost) invariably kills your car before the engine does.

Any attempt for a “forevermobile” would be better served to concentrate on some of the other factors that send cars to the crusher.

If I owned or serviced a vehicle that had the oil filter mounted in a way that made priming it possible, I’d do it. As it is, though, the filters on every vehicle I service mount to the side, making priming impossible.

I’ve NEVER EVER done it. It may be better to prelube the filter. But I really don’t think it makes that much of a difference.

The Jeep 4.0 engine was an engineer’s effort to thumb his nose at those of us who insisted on pre-filling oil filters. The filter was mounted inverted with a 4" stand pipe very near the motor mount and distributor. Using a Wix or Hastings filter a few ounces of oil could be poured in and the filter installed without spilling any by quickly flipping and dropping the filter down to the threads and spinning it on. Those engines seemed to run forever despite the dry start at every filter change.

Our two newest cars, GM cars have the new style filter w/o the steel outer can. The filters are located alongside of the engine, near the top end where the filters are easy to access. These drain dry every time after a few minutes when the engine is stopped and of course, are refilled when the engine is started again. This works well for the oil changer person as the filters are not a dripping mess of oil when they are removed.

Some here may be concerned with refilling the auto size oil filter at each oil and filter change. Our cars refill the oil filters at each engine start. GM has apparently determined that empty oil filter starts are not a problem due to adequate residual oil on the engine parts. Keep in mind that during an engine start, the loading on the engine is very light as compared to when the engine is pulling the car. I would guess that the filter housings hold about a pint or less of oil each.