pre filling oil filters? My opinion inside

I have noticed that several guys on here recommend pre filling oil filters when doing a service. Personally if i was you i wouldn't do this as IF done incorrectly can result in dirty/unfiltered oil getting fed straight into your main bearings. let me explain. most guys grab the new oil and fill the filter by the big centre hole in the filter, this is the outlet. A oil filter works by the dirty oil entering through the little outside holes, passing through the filter material then exiting through the big hole and heads to your main bearings. now if for some reason they new oil is not 100% clean or some foreign body/dust enters when you fill the filter it will get pumped straight into the main bearings!! personally i don't think a filter needs to be prefilled, yes there may be a lack of oil for a slight second whilst the filter fills, however there will already be a small amount of oil still on the bearings preventing metal to metal contact for this initial time. now if you insist on still prefilling your filter, here is the best way to do it. fill it through the small outside holes, yes this will take you ages but atleast when the oil goes into the engine it will be filtered! wayne

i've never pre filled my oil filter and never will, just dont belive its neccesary.

Well, you've stated a good reason to make sure you are careful in the process of filling the filter, not a reason to avoid it all together. The chances of foreign material getting into the filter when filling and installing are about the same as the chances of it happening when installing it dry... slim to none. In trying to avoid this very slim chance you are guaranteeing that there will be some amount of dry start damage. personally i don't think a filter needs to be prefilled, yes there may be a lack of oil for a slight second whilst the filter fills, however there will already be a small amount of oil still on the bearings preventing metal to metal contact for this initial time. The laws of physics aren't bound to how you feel "personally". Yes there will be a film of oil on the engine components that will protect them during cranking, but an oil film will not protect main and rod bearing surfaces from being damaged once the engine fires. Even at idle there is a massive amount of force being transfered through these bearings and until there is sufficient oil pressure, the film of oil simply gets displaced.

I agree there are high forces on initial start up, but lubrication is no worse then when the bike has been sitting and everything has drained back to the sump.

I agree there are high forces on initial start up, but lubrication is no worse then when the bike has been sitting and everything has drained back to the sump. The extreme forces continue past initial start up. Even at a sustained idle there is a huge amount of force on the bearings. The engine load is actually higher at idle than at say 3000rpm free revving. The lubrication is absolutely worse by not prefilling vs bike has been sitting. Even if the bike has been sitting, the oil filter media is still fully saturated with oil and as soon as the oil pump primes, you will begin to build pressure. By not prefilling, when you fire the bike up, the pump has to prime, then it begins pumping oil into the filter. Not until the filter has completely filled will it actually start moving oil to the bearings. This causes a much longer delay in oil supply and pressure.

still i'll continue to not pre fill my filters

Still I'll continue to pre fill my filters.

still i'll continue to not pre fill my filters :thumbup Wow, bested in a technical discussion of the pro's and con's, so you'll just keep doing it "because I wanna". :lol If you want to make a conscious decision to ignore the facts that's fine. Just don't post this BS where people who legitimately want to learn the truth might accidentally believe it.

Still I'll continue to pre fill my filters. +1... Always have always will.

i may be missing something, but it seems some points people making are a bit contradictary. in one method to change oil, people recommend turning over the motor to get all the oil out. in response to questions about the motor turning over without oil, they say a fresh coat of what was in there is good enough. yet people recommend priming the oil filter to keep the engine from turning without oil pressure. but it was just coated with oil, wasn't it? now some of those same people say that it's bad to turn the engine over without oil pressure. now, the oil that's coated is no longer sufficient as it was previously. :dunno

No contradictions at all. With my oil change method you are cranking the engine (but not running it) with no oil pressure. This is fine. Parts are lubricated and will slide with little friction. Starting the engine with a delay in oil pressure is bad. You want full oil pressure as quickly as possible once the engine is running. Not pre filling the filter delays this and causes unnecessary wear.

When your turning the motor over to get all the old oil out your not running the bike.... Got fire and fuel turn off.

No contradictions at all. With my oil change method you are cranking the engine (but not running it) with no oil pressure. This is fine. Parts are lubricated and will slide with little friction. Starting the engine with a delay in oil pressure is bad. You want full oil pressure as quickly as possible once the engine is running. Not pre filling the filter delays this and causes unnecessary wear. um, the other guy is right you are contradicting yourself. on one hand you say its bad for the engine to crank with no oil pressure yet your oil change method it's fine to crank the engine for 15 seconds without oil!! my way of not prefilling filters doesn't say that the engine has to be started why not install a dry filter and crank over in diag mode to get pressure before starting? also i didn't say prefilling was bad AS LONG AS IT'S DONE CORRECTLY, but i'm sure 99% average joe's would fill via the large hole, which is putting unfiltered oil straight into the main bearings. sorry but i like the oil going to my bearings to be filtered and hence will not fill my filters. please keep this from becoming a shitfight, let the educated public make up their own minds

um, the other guy is right you are contradicting yourself. on one hand you say its bad for the engine to crank with no oil pressure yet your oil change method it's fine to crank the engine for 15 seconds without oil!! my way of not prefilling filters doesn't say that the engine has to be started why not install a dry filter and crank over in diag mode to get pressure before starting? also i didn't say prefilling was bad AS LONG AS IT'S DONE CORRECTLY, but i'm sure 99% average joe's would fill via the large hole, which is putting unfiltered oil straight into the main bearings. sorry but i like the oil going to my bearings to be filtered and hence will not fill my filters. please keep this from becoming a shitfight, let the educated public make up their own minds Maybe you should read more carefully before telling me what I am saying. This is really pretty simple, try to stay with me: Cranking the engine without oil pressure = okay Running the engine with a delay in oil pressure = bad Still with me? Oh my god, unfiltered, brand new oil!?!?!?!? Newsflash, new oil doesn't have a need for filtration.

also i didn't say prefilling was bad :lol Have you read the title to your own thread?

:lol Have you read the title to your own thread? :stpd: WTF!? :confused: , pre fill for me :fact

i never knew about pre filling. so you fill the filter about half way?

Its like tires or your choice of oil..... Everyone has their own opinions. Browser..... if your going to say you didnt say something, make damn sure its not the title of the thread.....:lol

i pre fill my filter but i use a paper paint filter most paint shops will just give them to you there realy cheap and it will filter anything out of your oil.

i pre fill my filter but i use a paper paint filter most paint shops will just give them to you there realy cheap and it will filter anything out of your oil. Out of curiosity, have you ever filtered something out of brand new oil?

i never knew about pre filling. so you fill the filter about half way? You can actually fill it to the brim, then swirl it around a bit as it absorbs into the filter media. I usually fill it again about halfway.

Also, a lot of times it depends on how the filter is mounted..... If its vertical its cant hurt to fill it. Try and fill one horizontally mounted and your just asking for a mess......

Also, a lot of times it depends on how the filter is mounted..... If its vertical its cant hurt to fill it. Try and fill one horizontally mounted and your just asking for a mess...... never had a mess before :dunno, but I only fill it up 3/4 of the way and let it soak in before I put it on

You can actually fill it to the brim, then swirl it around a bit as it absorbs into the filter media. I usually fill it again about halfway. ok. never had a mess before :dunno, but I only fill it up 3/4 of the way and let it soak in before I put it on probably going to do it this way next time.

:lol Have you read the title to your own thread? :lol now who is contradicting themselves :lol

Browser, go find a engine with hydraulic lifters, drain the oil out, let the engine sit for a couple minutes, then put in fresh oil without prefilling the filter, listen as the lifters clatter from no oil for a few seconds....then figure out why its bad to do that to your bearings.....BTW, Im changing your thread title, your not going to hurt other peoples engines for your lack of understanding of engine lubrication.

Here's how you fix this problem. Install an Oil Precharger (http://www.amsoil.com/storefront/amk.aspx), wait for the oil pressure to build and then start the vehicle. No more dry starts. Although on the bike you'd have to run the remote filter to install the precharger.

What I still fail to see is how damaging it is to the engine without prefilling vs prefilling. Is the life of the engine decreased in half, 3/4th, etc, etc? Kind of like the which oil is best question, no one has done substantial testing to prove that severe engine degredation over the life of the engine. A majority of riders don't even keep bikes long enough to perform long term testing anyway, they change bikes more than they change their underwear over time. :) I prefill, but that's if I actually remember to. I say just hurry up and change the oil and get out there and ride. :lol

the whole argument is based on what makes sense to people. yes, less unlubed time is better, but better for what? i've never heard of a consumer vehicle having or having available a prelube/prepressure setup. in an industrial environment they're common, but those engines deal with stresses and loads well beyond any vehicle. i've never and have never known anyone who prefills filter in cars, which the same resoning would apply. and i know many cars that are extremely old and have many miles. so as it may not be as good, it's not that bad and will not(itself) shorten the life of the vehicle to a point that you wouldn't have gotten rid of it already anyway. performance on the other hand, maybe. when you start talking about valve clearances and compression and cylinder/piston/ring condition, those can play a part. although, only hardcore racers who know when they lose 1/2 hp would care about something like that. my general rule is to let the engine(car or bike) idle for a minute or so to circulate the oil before i drive it. though precharging the oil system would be better, i think it's overkill for the use of consumer vehicles. just my opinion, though. to each their own.

the whole argument is based on what makes sense to people. yes, less unlubed time is better, but better for what? i've never heard of a consumer vehicle having or having available a prelube/prepressure setup. in an industrial environment they're common, but those engines deal with stresses and loads well beyond any vehicle. i've never and have never known anyone who prefills filter in cars, which the same resoning would apply. and i know many cars that are extremely old and have many miles. so as it may not be as good, it's not that bad and will not(itself) shorten the life of the vehicle to a point that you wouldn't have gotten rid of it already anyway. performance on the other hand, maybe. when you start talking about valve clearances and compression and cylinder/piston/ring condition, those can play a part. although, only hardcore racers who know when they lose 1/2 hp would care about something like that. my general rule is to let the engine(car or bike) idle for a minute or so to circulate the oil before i drive it. though precharging the oil system would be better, i think it's overkill for the use of consumer vehicles. just my opinion, though. to each their own. Very well stated......:thumbup

Ok...so I read to pre-fill here a while back... I changed the oil last week...heres what happened...(on a lighter note to relieve tension) I was going to pre-fill this time (third oil change). I got it all drained and pre-filled the new filter 3/4 ways and let it soak in for a horizontal app. I got it on, and started to put the drain bolt back on and while doing so...the socket slipped and landed into the old oil. I went in bare handed and dug it out... while doing so...it slipped outa my hand and landed in the tool chest and on the allen wrenches...I wiped off my hand and grabbed the oily allen wrenches...to clean, I sat up to a sittin position on the garage floor. I was going to wipe them off and they slipped outa my hand and landed on my NEW SHORTS that I WASNT going to get anything on. GRRRRR I got mad and went to grab a clean rag nearby to wipe off my crotch...and hit the bottle of new oil I just opened to pre-fill the new filter...BUT DIDN'T KNOW it till I stood up and saw a PUDDLE of new oil underneath my FRONT TIRE about 2' in diameter. I WAS ON FIRE!!! Then I was getting mad... I then started to clean my front tire as fast as possible, and dig down in the groves to make sure I got all the oil off the tire... I swear thats how it went down...it sucked at the time... but its funny now... So Thumbs down to pre-fill that day,..and as far as the oil in the center of the filter...GIVE ME A BREAK! Nothing in new oil is going to hurt the bike unless your button popped off your shirt and got in there. lol - Theres more crap at the bottom of the oil pan than anything you could put in with new oil. lol :lol

Ok...so I read to pre-fill here a while back... I changed the oil last week...heres what happened...(on a lighter note to relieve tension) I was going to pre-fill this time (third oil change). I got it all drained and pre-filled the new filter 3/4 ways and let it soak in for a horizontal app. I got it on, and started to put the drain bolt back on and while doing so...the socket slipped and landed into the old oil. I went in bare handed and dug it out... while doing so...it slipped outa my hand and landed in the tool chest and on the allen wrenches...I wiped off my hand and grabbed the oily allen wrenches...to clean, I sat up to a sittin position on the garage floor. I was going to wipe them off and they slipped outa my hand and landed on my NEW SHORTS that I WASNT going to get anything on. GRRRRR I got mad and went to grab a clean rag nearby to wipe off my crotch...and hit the bottle of new oil I just opened to pre-fill the new filter...BUT DIDN'T KNOW it till I stood up and saw a PUDDLE of new oil underneath my FRONT TIRE about 2' in diameter. I WAS ON FIRE!!! Then I was getting mad... I then started to clean my front tire as fast as possible, and dig down in the groves to make sure I got all the oil off the tire... I swear thats how it went down...it sucked at the time... but its funny now... So Thumbs down to pre-fill that day,..and as far as the oil in the center of the filter...GIVE ME A BREAK! Nothing in new oil is going to hurt the bike unless your button popped off your shirt and got in there. lol - Theres more crap at the bottom of the oil pan than anything you could put in with new oil. lol :lol SUX2BU. :lol I put the drain bolt back on before the filter goes on.

SUX2BU. :lol I put the drain bolt back on before the filter goes on. Had the drain bolt on, just hadn't tightened it down yet...that wasn't related to the problem though the old oil in the drain pan should have been removed...wasn't thinkin... it does suc2bme, thanks 4 takin the time to reply though...

I love these kind of threads.

i've never and have never known anyone who prefills filter in cars, which the same resoning would apply. Are you kidding me? I've NEVER met or heard of anyone familiar with autmotive technology NOT pre-filling their oil filter. In fact, the only time I've ever heard of anyone not doing it is on their first oil change. I was always taught to fill it. IIRC it was even in some owners manuals/repair manuals for vehicles I've owned and sold since then. I guess it really all filters down (pun intended) to how comfortable you are with running your engine without any oil pressure. I've never been worried about buying a used vehicle or bike from an automotive enthusiast. After reading this thread though I'll be more wary from now on. Guess I'll have to ask them if they pre-fill or not. I'll pass on ANY that I find who don't pre-fill.

I've never been worried about buying a used vehicle or bike from an automotive enthusiast. After reading this thread though I'll be more wary from now on. Guess I'll have to ask them if they pre-fill or not. I'll pass on ANY that I find who don't pre-fill. talk about being overly dramatic

talk about being overly dramatic +1 My 93 Accord had over 200K miles on it when I sold it and never filled an oil filter with every 4000 mile change........Can it help....... maybe, can it hurt it, highly unlikely...... All the oil does not drain completely out of the motor when you change it. :secret: Some people do it, some dont...... but its not going to blow your engine up if you dont.... If you do, can it help prolong the life of the motor? Theres no way to possibly tell this, so this discussion can go on for ever without any resolve...... To each their own......

Are you kidding me? I've NEVER met or heard of anyone familiar with autmotive technology NOT pre-filling their oil filter. In fact, the only time I've ever heard of anyone not doing it is on their first oil change. I was always taught to fill it. IIRC it was even in some owners manuals/repair manuals for vehicles I've owned and sold since then. I guess it really all filters down (pun intended) to how comfortable you are with running your engine without any oil pressure. I've never been worried about buying a used vehicle or bike from an automotive enthusiast. After reading this thread though I'll be more wary from now on. Guess I'll have to ask them if they pre-fill or not. I'll pass on ANY that I find who don't pre-fill. well, to each their own. you should get out more, because most people don't prefill. how many joe schmoes prefill? probably none. and their the ones with half a million miles on their 20yr old beaters. less "no pressure" time is obviously better, but i guarantee you that it won't make a difference in the time you'll own the bike or car. instead of prefilling, why don't people do what they do when draining and just turn the engine over without starting it? that would fully prime and pressurize the system, which would be much better and more effective than simply filling the filter, which does nothing to fill the rest of the system.

At the very low rpms turned while cranking it can take a while before a dry filter gets fully filled. In reality, your best bet is to fill the filter and do a little cranking first.

What i find funny is that your worrying about dust and such getting into the filter hole, which is very small, but the fill hole for oil on the other side of engine is bigger where you put the oil in, also when you use a funnel to pour the oil in, is that 100% clean? Dust and stuff can get in threw there. Any little tiny particles will find way in there when you put filter on, or fill oil, even tho you can't see them floating around in the air easy, dust is everywhere. Curby

What i find funny is that your worrying about dust and such getting into the filter hole, which is very small, but the fill hole for oil on the other side of engine is bigger where you put the oil in, also when you use a funnel to pour the oil in, is that 100% clean? Dust and stuff can get in threw there. Curby True, but that oil gets filtered before it reaches main bearings unlike the pre filled filter oil (judging the filter was filled by the big centre hole and not the little holes)

Well I just read all of the above posts. Some quite amusing actually. I had my own thoughts on pre-filling the filter, but was interested to read other opinions. Personally I have never pre-filled the filter on any oil change [ Car or bike ]. Last time I changed my bike oil I made quite a mess. Although you try to be carefull. Have good drain pan, funnel, Rags at the ready ect the reality is It can be a messy job and you can and most likely will spill some oil. Anything with the potential for more mess is out for me. Anyway to try and draw some towards a conclusion. What do you do when you have a lot of opinions but no facts ? I thought I would consult my 2007 R1 Service manual [ Section 3 11-12 ] as after all they built the thing. No mention of pre-filling the oil filter in there. Good enough for Mr Yamaha, good enough for me.

i think you would be hard pressed to find prefilling filters in any workshop manual for car, truck bus, bike etc. The manuals at work for caterpillar V16 industrial motors doesn't mention anything about prefilling filters and we have always be taught not do as POTENTIALLY contaminated oil could enter into the main bearings.