When changing my oil, should I prefill my oil filter with oil before installation?

It seems like a lot of people get tired of talking about oil but not me, I love it. I think it's one of the least understood yet most important keys to reducing engine wear and extending the life of our engines. As Ben Strader, who taught me engine development and tuning at EFI University, always says "application dictates chemistry". And by having your used oil analyzed at labs like SPEEDiagnostix or Blackstone after each change, you can see what oil your engine likes best based on how you use it. So here's a fun little poll, on a sometimes controversial subject, to get more people thinking about how they care for their engine.

Interestingly, when using thinner oils, it absolutely matters. The testing showed that the wear metals increased when not prefilling for a 5W-20, but they did not change for a 20W-50. This also correlates with why we recommend heavier viscosity oils to be run in these engines, based upon max oil temps. A thicker oil film strength is able to still protect the rod bearings during momentary lapses in oil pressure. Watch this video for more information or fast forward to 33:00 to see the results. You Tube

I've been filling filters for decades, on all engines. Including on m96 since last century. Never even 1 engine failure. But here on our forum, its been stated filling oil filters on m96 causes engine failure.

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I've never understood the concept of filtering new oil being more important than preventing the equivalent of oil starvation.

Toyota 4.0L V6 Ferrari 'Colombo' V12 Continental aircraft engine

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Understand where you're going here, been there done that. All those above pics with inverted oil filters will spill some oil when removing them. Nothing a few well placed shop rags/old towels can't catch almost completely. The Toyota even has a catch basin surrounding its filter, to catch spill. Might even be a drain hole/tube on the catch basin. I've had many inverted filters over the years. Not a problem. Just do the same shop rags technique for removal when installing a full filter. I fill the filter a few times till the media absorbs the oil and filter is full to top. Then bring filter carefully to the filter holder and quickly invert it and spin it on quick, for very little spill the rags can catch mostly. then wipe/brake clean/blowgun away any mess left over if any.... Takes some planning and quickness but can be done easily without any more mess then happens in filter removal. But make no mistake, inverted filters are more messy compared to our m96 canister filter. Still no reason not to fill them and prevent extra seconds of oil starvation. jmho

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Agree... The word going around on web, is plastic pieces break off the bottle top retainer ring and fall directly in the center of filter supply port. And oil changer doesn't see this. Then once oil pressure is introduced in system the plastic bits go directly into main oil gallery and block it completely/partially. Supposedly engine failures have been caused by this more than once. Well, to me its just as easy for some Neanderthal oil changer to drop some debris in same filter port with empty filter. might not be pieces of the bottle top retainer ring, but might be globs/chunks of greasy under car sand/dirt globs that find their way into filter port.... jmo

[delete me]

I tried non-filling twice and my engine very briefly did not sound happy when I did that. Never again, though I do understand the point that some make that pre-filling a 996 oil filter is a bad idea on a freshly rebuilt engine due to possibly air lock.

1999 3.4 with the IMS Solution I was told NOT to prefill the oil filter by the certified installer and LN Engineering.

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I think the best way to know for sure is to try it both ways, get a used oil analysis after each, and see which option (if either) has the least amount of wear on your engine.

Not that it matters but I can�t remember if it was a LN or a FSI recommendation. I don�t but have no reason why I don�t.

I was told by the guy that reconstructed my engine, who knows a lot more about the m96 engine than I do, not to prefill the oil filter. This instruction was not just for the fresh engine. Good enough for me.

Very curious to hear the reasoning behind those who say not to prefill. Other than because, "so-and-so said so." Did they elaborate as to why?

Restart after oil change - unfilled filter - should be start engine, immediately shutoff, start engine, immediately shutoff. Start engine and you should have good oil pressure. Supposedly you cannot build enough oil lift and pressure using just the starter to spin the engine - thus the several start/stops. -Tom 2003 C2

Not going to happen on a Mezger engine. It takes less than thirty minutes to change oil. I can't imagine critical parts becoming oil-free in that amount of time. Try taking a screwdriver and dipping it in oil, then hang it up for a few days and see how dry it is. Anyway, I don't even think about when I change oil. I drain it, change filter, fill it, then start the car like I always have for the last 26 oil changes of its 156K miles. Do whatever voodoo you want to do, but I think people over think the issue when they could be driving.

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My �19 BMW B58 motor doesn�t leak a drop with the inverted oil filter. Smart design. Once cracked open, it all drains out. I do this first, then start draining the oil from the pan. However, I�m not sure how I could prefill this filter. I�m sure it would all spill out. I�m pretty sure engine designers have thought of this on these designs.

Quotes source post: 19560126

I don't need to know why although it was explained. Sometimes I have found that when I find the expert that I trust I let them do their job. Kinda like a heart surgeon. I don't need to know all the hows and whys of heart surgery. I just want him/her to know what they are doing and I plan to follow what they tell me to do pre and post. To me it boils down to do due diligence then trust.

Quotes source post: 19560126

When the oil is drained, the oil pickup drains, as well as bits between the oil pump and the filter. Inevitably there will be air between the oil in the pan and the filter. The oil in the filter creates resistance when the car is started and the oil pump starts pumping. Initially the pump is trying to push the oil out of the filter with air, which compresses. If the filter is empty, the pump has an easier time pushing air/oil, and can push enough air to get oil up the pickup and into the pump, so it doesn't lose it's prime. Speculation: If you are like me, and you drain your oil for 15 minutes before refilling, you probably will not have an issue pre-filling. But if you drain overnight or for a prolonged period, you may have issues if you prefill. I do not prefill.

the trick is to buy a car with an engine that sounds broken no matter what you do when you start it up

Quotes source post: 19560159

I was going to include BMW in my list of pics above. Mercedes Benz too. The fact is that the great majority of oil filters cannot be prefilled sufficiently for it to to make a difference. Plus at least one prominent and hugely experienced engine builder strongly advises against it. Folks can continue to argue if they want, it's a free country.

I know I�m going to sound like a moron but does this also include spin on filters?

None of this would matter if manufacturers would have included pre-oilers in their cars. Some hybrids do. EVs are taking over, so now it really doesn�t matter.

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Not everyone will get that.

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Lake and I have discussed this and there are almost always exceptions. The M96 is one of them. Not that it happens very often, but we do get calls once in a while with people doing oil changes where the engine won't build pressure when the filter is pre-filled. It has never been an issue installing the oil filter without pre-filling it and there are many applications where it is physically impossible to do so because of filter placement and/or orientation.

was there ever a public service announcement about pre-filling oil filter causing engine failure..?

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Rattle & smoke on startup, please.

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Its like a box of rocks when it sits for a few days.

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I just tell people "oh that's where my 10mm socket went!"

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My brother's 992 GT3 Cup car has a pre-start procedure that cranks the engine several times for 2 or 3 cycles. How many cycles seems to depend on how long ago the engine had been run. First start of the day seemed to take 3 cycles. After the pre-start cranks, the next crank cycle starts the engine. Apparently it is all software driven. I guess it is a pre-oiler of some sort? The attached pic shows the dash display. Looks pretty high tech... Seems like a good idea to me. Sure wish my M96 had a pre-oiler. Doug

Quotes source post: 19558373

All of the "correct" filters for the Ferrari Colombo V12's have an internal standpipe so they will still retain the oil when the engine is shut off (even though they are mounted upside down). Baldwin is the preferred filter, followed by Ufi. Frams are not recommended. I assume Frams were probably good quality back in the 60's, but reportedly Fram has had crap quality for decades. For the 996, I would have thought pre-filling was better on a logical level, but given the potential concerns, I won't be prefilling my 996 filter.

I did discuss the topic of pre-filling the M96 oil filter again and he did mirror my sentiment. The video was not to be taken as a one-size fits all recommendations as there are always exceptions to every rule.

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Very neat! This is very similar to how Jake recommends building oil pressure on the M96 engine. On a fresh rebuilt it can easily take 5 quick on/off cycles to fully prime the oil system.

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Hi Charles. Couldn't agree more. The most interesting part of the video I thought was that the heavier weight oil made it a non issue. Regardless, if these posts cause people to think a little more about the impact their oil has on wear and the advantages of monitoring wear with UOA's, then it's a win in my opinion. if they start trying different oils like M1 15W-50, DI40/DI50, or a Motul 300V 5W-50 to see what impact they have on their engines wear, then it's a huge bonus. On the oil filter question specifically, do you all have any data or test results you can share as a comparative? We'd be happy to help come up with some if not. Even just looking at oil pressure traces using the 3 different methods (fill, no fill, no fill 5 starts) might be somewhat revealing. Thoughts?

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I can for sure tell you we've had countless shops try to build pressure by pulling the fuel pump relay with the spark plugs out and wipe out all the bearings in the process. The start/stop method or using a pre-oiler are the safest bets for priming a new engine. I personally do not have data for fill vs no fill for the filter, but I know we have had calls with no-pressure at start up as has Jake associated with pre-filling the filters. That's why we put a label on every 1042 and 1348 filter we sell and ship that says not to pre-fill it. I regularly buy pretty much every 1042 and 1348 filter that crosses with the Napa Gold/Wix filters and cut them apart to check for changes or manufacturing/quality issues. As long as you don't use one of the Chinese Napa Golds (not made by Mann-Hummel/Wix), you're good. We also list alternate filters on the website.

Little confused here... Most all engine builders require new engines to be pre-lubed till pressure is seen on gauge, before initial start up..? Or warranty is void. Only exception I've seen for high $$$$$ engine builds is when builder does break in on his dyno. And even then most still pressure pre-lube after engine installation. I find a empty pressure port or tee into the sender unit and dump my full accusump into engine and commonly see over 60psi in engine. And start engine while pressure is still showing on gauge. Make no mistake, Pre-lube will fill filter full and pressurize it . jmho

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Given that the topic is pre-filling I think that standpipe is after the fact. Interesting to know though, thanks.

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Yeah, the more expensive/advanced the race car, the more pre-start procedures are done (F1 pre-warming fluids and such).

I think it's very important to make a distinction that all this really applies to regular oil changes and NOT pre-filling on an initial start up after an engine rebuild. That's not a typical scenario we deal with so let's focus on this from the perspective of a regular oil change as I'm seeing mention of priming a new engine. I have typically never pre-filled my filters as prescribed on here but upon an initial start up after an oil change I would notice about a 1 Mississippi to 1.5 delay in the oil pressure gauge shooting up and showing pressure. I'll be doing a new oil change soon with FR50 on my Slakker 4.1 and plan to fill the filter and observe if there is any difference in how fast it builds pressure. I also have UOA from last oil change where I did not pre fill and will have one again in 5k miles with pre-filled filter so will share that analysis with Brandon and here to see if there are any differences on the wear side. I don't know but curious! With thicker oil, I can only assume that more of the film will be left on bearing surfaces and etc providing better protection vs thinner oils. Again, I can only assume that oils like DI50 that are 15w50 will provide even better protection on cold start up.

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The standpipe is definitely after the fact (subsequent starts after an oil change), but I assumed the point of your first post with the photos was to show examples of filters that start empty all the time because they are mounted upside down (Ferrari) or tilted downward (Toyota, Continental). Not sure what Toyota does, but you wouldn't want to run a filter without a standpipe on a Ferrari (I'm sure there are plenty without a standpipe that fit). It kind of shows the importance of getting exactly the right filter for a given car. I guess Napa old style oil filters versus Napa new style/Chinese-made oil for 996 in that other thread is another example ( https://rennlist.com/forums/996-foru...2-filters.html ).

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Actually, in the posts above mine, Charles was just talking about pre lubing new engines and problems others have with "wipe out all the bearings" quote_ "I can for sure tell you we've had countless shops try to build pressure by pulling the fuel pump relay with the spark plugs out and wipe out all the bearings in the process. The start/stop method or using a pre-oiler are the safest bets for priming a new engine ." First I'd heard about 'don't pre fill filter' was when a thread came up some years ago from a well respected forum member that informed us his new rebuilt engine by 1 of the biggest builders here, had bearing failure in under 100 miles. The engine builder looked over engine and his failure analyses was that 'oil filter was filled' and was the sole reason for the failure. Hence my confusion and question.... Thats why I asked above if ever a PSA was given about this. To this date no one has replied to my above post/question, so assume there was never a PSA...

I have had nearly 100 oil changes over the past 22 years on 67k miles. No clue whether my shop prefills or not. But I am going to ask just for the heck of it. Whatever they are doing seems to work well.

We use a Tilton oil pump and remote filter to perform a 5-minute oil flush of our newly rebuilt engines while manually rotating the crank. Since our primary sealant is anaerobic, this allows us to wash a good amount of it out, verify that the engine can sustain oil pressure without any signs of seepage, and serve as a final safeguard to wash out any vapor blast media that may have somehow remained after power washing, ultrasonic cleaning, and a final jet wash. When we moved to this process from using a pressurized prelube oil tank to fill the engine, we saw a nice improvement in our break-in UOA's and have maintained the practice ever since.

Quotes source post: 19570341

They were examples of filters that cannot practically be pre-filled during an oil/filter change service.