First of all I was all for pre-filling the oil filter to reduce the time of the dry start after an oil change (I got oil pressure in 2 seconds). But my last experience has me wondering if it was worth it.

Here's what happened. After changing the oil and filter (prefilled to the brim) I took the vehicle for a quick spin and then checked for leaks. Unfortunately for my peace of mind, there was fresh oil dripping down the side of the oil filter. Not a bunch, but enough to make me nervous. I tested the tightness of the filter and it was tight. So I wiped it off and took ot for a similar short trip and there was still some fresh oil visible on the outside of the can. I did this ritual for 4 short trips until finally there wasn't any more oil visible.

My conclusion from this is the oil that was dripping was likely just some oil that had spilled onto the rim of the filter from the pre-fill and wasn't a leak at all. But the hassle and lack of confidence had me questioning the value of the prefill in this case. I think I would have been better off with an extra second or two of dry start if it had prevented me the hassle and worry that followed.

What do you think?

 

I think it's worth it, if possible. Rgiles, your filter is probably mounted at an angle that prevents filling the filter completely, right? One of my vehicles is like that, and I just partially fill the filter to keep the oil from running out.

My Cherokee's filter is mounted almost upside down, so I can't prefill it. I try to do a quick oil change right after shut-down, hoping that enough oil remains on the moving parts to prevent a dry start.

 

I think it's worth it, especially if you have a turbo charger. I not only minimizes engine wear, but turbo wear. The funny thing is that the new Power Stroke has the filter mounted upside down on the top of the engine, so it virtually eliminates the possibility of doing it.

 

Prefill if you can. Whatever you do, don't let the engine sit too long with no oil in the crankcase. Some members have reported problems withrepriming the pump if the case is empty and the filter is removed etc and left for long periods.

I once drained the case, left the plug out and let it sit over night. it was cold and the oil(synthetic) was also cold when I pourde it in the next afternoon. The filter was empty.

When I fired up the truck, it took maybe up to 30 seconds for the oil light to go out. On my truck normal dry filter start up is maybe 2-3 seconds. So I am guessing I have "broken' The prime on the pump and was sucking air to fill my empty filter.

My filter sits almost vertical so it it is empty it has to fill up before the rest of the engine gets oil. This type mounting would be especially easy to prefill since no oil would pour out.

I used to waver back and forth on wheter to pre fill or not, but that experience convinces me it might be more important than I thought.

Good Luck,

Jim Henderson

 

Instead of filling it exactly to the top, why not just try to fill it to the bottom of the threads, or just maybe a 1/4'' under the threads?

That way you won't have oil sloshed around when you spin it on, and still have the peace of mind of a pre-filled filter!

just a thought,

 

i always prefill on the premise it takes just a few seconds of my time, it cant hurt the engine and i believe prefilling does speed oil circulation. as preranger says, i fill to about 1/2inch from the top on my vertical filter and there's no problem.

 

i always prefill my oil filters.

 

In my pinion this pre-filling the oil filter is a waste of time. The reason I think this way is do to a number of reasons! If you pre-fill the oil filter the oil galleys are still dry!! So it will still take the same amount of time for the oil to circulate from the oil pan to all the oil galleys, whether or not you pre-fill the oil filter. SO if someone has some good reasons as to why they pre-fill the oil filter please share them with me and the other users. So far all of heard from the number of times this tpoic has been discussed was that I do it for peace of mind or an old timer mechanic that I trust let me in on his little "secret"!!

 

because if you prefill the oil filter with oil, your oil pump has 1 less quart of oil to pump before it pressurizes the main galleries. have you ever looked at a mechanical oil pressure gauge when you started a car with out prefilling the filter?no your not gonna have instant oil pressure as soon as the engine turns over because the galleries are empty, but if your oil filter is full it will imediately start pumping oil directly into the block. otherwise, the filter has to fill with approx. 1 quart before this happens. 75 to 90 % of engine wear happens at startup. if you run your engine without filling the oil filter after changing it your are running the engine with no oil pressure for a longer time! i've changed oil in hundreds of cars and trucks and i can hear the bearings knock until the oil pressure raises up. i never prefilled any filters at work and can notice the time differance in the amount of time it takes the engine to build oil pressure. if you run the engine say three seconds more without oil pressure by not prefilling the filter, and change oil every 3000 miles, by the time you get to 150000 miles and changed the oil 50 times, the engine has run 2and a half minutes more without oil pressure! you think that isn't gonna have any effect on wear? what would happen to your engine if you ran it for 2 and a half minutes with no oil? and how much extra time and effort does this take? maybe 20 seconds? i say fill the filter every time.

 

Ok, I respect your point of view. Though I would have to dis-agree with the part that you said about the pump has one less quart of oil to pump. I think of it this way, the engine doesn't know if theres oil in the filter or not. So it doesn't just by pass the filter it still pumps oil to the filter before it pumps oil to the rest of teh engine. Correct me if I'm wrong. So if it doesn't I don't think it helps shorten the time of a dry start. By the way the bearings and rockers and all those other parts in the engine are coated with oil so, they will never experience a dry-start. Also if I agree with what you said about a total of 2 1/2 minutes of running your engine with out oil. Running it for a few seconds at a time with-out oil is much more different than running it without oil for 2 1/2 minutes at once!!

 

I prefill the oil filter on my Explorer because since it fits vertical it won't make a mess. I figure if there is anything that I can do to help prevent any more wear then why not. As far as it being a waste of time, I fill it while the old oil is draining, I get about 3/4 of a qt. in before I install it. So there really isn't anymore time used.
I have a T-Bird Turbo Coupe, and was told by Ford that one of the most important things I could do was prime the engine after draining the oil. To do this they say after new oil and filter are in, to disable the ignition and to crank the engine a few seconds.
I can't prefill the filter because it fits in sideways.
This car has a conventional distributor, so I can disconnect and ground the coil wire. On newer vehicles disabling the ignition maybe either more involved or can't be done without doing damage to the ignition system. So prefilling maybe the best ya can do.

 

Thanks for all the feedback. I'm all for pre-filling in principle, it just turns out in my case I sorta wished I hadn't because of the worry factor. I don't think an extra 2 seconds before pressure will significantly change the life of the engine, but a "fake" leak could shorten mine

Next time I believe I will avoid filling it to the top as some have suggested so I can be sure any leaks are legit. I agree that long drains are probably worse than short drains because of the loss of prime. I usually only drain until it's a drip which is less than 30 minutes.

I'm going on the 5000 mile drain interval so it will be 4-5 months before I need to change it again on this vehicle.

 

ivv got a 91 ranger 4.0 with 260,000 miles on it , uses very little oil. i have NEVER prefilled the oil filter.

 

I add a little oil to the filter and then tip it sideways a little while slowly spinning it. That way the oil soaks into the media. I repeat until it won't soak up any more oil and there's only about 1/2" of oil in the bottom, no mess.

The filter doesn't have to be filled to the top with oil. Once the filtering media is pre-soaked, it only takes a second or two for the filter to pack and you get full pressure almost immediately.

I started pre-filling when I got my first turbocharged truck. Now I do it out of habit for all my vehicles, turbocharged or not.

For those who say it's a waste of time, I say the whole point in changing oil ourselves isn't to conserve time. It's to do a better job, at our own convenience and save a little money while gaining the satisfaction that there is still something we can do ourselves that doesn't take a tech school degree.

I mean, I could argue that wiping the area around the filler cap or wiping the pan or drainplug before you screw it back in is a waste of time. But you're still going to do it, right? It's all just part of our little oil change ritual that we enjoy doing.

Now just remember to turn your old filter over and let it drain for a few days before you put it in the trash...

Scott

 

Ive drained my oil, takin' a nap, then filled the case when I woke up without priming the filter, no problems. OIl pumps spit lots of oil and don't need to be primed. I save time by sucking the fluid outta rear ends with my trusty old 300 six oil pump it's worn out, and a couple spins with a 1/4" wrench gets the oil flowing.
I can't see any dangers posed by not priming the filter