Magnets and motor oil (a summary)

[DanielinTheLions]

Recently my curiosity drove me to explore what BITOGer's were saying about using magnets in engine oil. Below is a summary of the comments that others have made. In most cases I've provided a link to one of the comments which was making a claim, however, somehow I did lose track of some of the links. The are broken down results into positive, negative, and technique comments.

Positive:

Several BITOGer's have suggested that magnets may catch particles which would be too small for the filter to catch. In one thread particles were examined under a microscope showing that what the magnet caught was below the filter's capacity (1). Another mentioned that particles all the way down to 2 microns cause additional wear thus if the magnet catches these it could be helping (2).
Additional, comments mention that some OEM oil plugs contain magnets and that transmissions often have magnets in them suggesting that some manufactures think magnets are a good idea (3). Often a threat will include at least one post which states that it seems like even if it can't be proven that magnets help it seems like it can't hurt so if it improves your comfort level use them (7).


Negative:

There were also plenty of negative comments. In many threads there was at least one skeptic who didn't think magnets would catch particles smaller than the filter element can catch, or that if there are particles are large enough for a magnet to catch it suggests that really serious unusual wear is occurring (5, 6). Additionally, many have suggested that the same wear still occurs and even if iron is lower in UOA it's only because the wear particles are on the magnet and not detectable in the UOA (unfortunately I lost the links for these posts...but there were plenty of them and they can be found using the search feature). In one comments a user referenced an article from Noria's Machinery Lubrication which suggested that the use of magnets may cause particles to be released in a particle cloud, apparently from a bust of flow or jolt...etc, and thus resulting in a clog upstream (4). In the same comment (and in other threads) the concern is raised that this could lead to magnetized particles which could then stick to critical parts of the engine. Probably the most negative comment though was one which stated that in a study conducted over 10 years ago by a fleet operation the use of magnets made virtually no difference in UOA vs a control group that was not using magnents (8).

Techniques:

A few have suggested that placing a magnet on the oil pan might be a good technique (9). However, in the same thread other commented that this is probably a bad plan as particles may remain stuck to the pan even though the magnet is removed before draining the oil. Thus, this technique could lead to years of particles collecting in the same place and possible resulting in a cloud of particles being released sometime in the future. So the recommendation is to place magnets on the oil filter. In almost every thread there is at least one post advocating the use of magnets from old hard drives (10). At least one comment mentions that they last a very long time (at least 8 years) in spite of the high heat conditions. Other comments mention magnets that can be placed inside the return side of the filter, though some BITOGer's are concerned about flow restriction with this (sorry lost the link). Another post mentioned epoxying a magnet to the oil plug and others have mentioned simply purchasing a magnetic drain plug (sorry no link again). Additionally, there are plenty of after market magnets which can be purchased which will attaches to the side or the bottom of the filter. This link provides a pic of what one side mounted magnet caught (11). Of course there are plenty more pics if you search the filter forum for magnet.

Quick Summary:

The pictures posted in the forums clearly show that magnets in oil do catch particles of iron which are in the oil. However, it seems like the only scientific information we have to go with here is the fleet study which indicated that magnets don't really make a difference the actual wear that is occurring. Additionally, the concerns about particle clouds seem like a bit of a deterrent to me. I still have some other concerns such as could additives be trapped by the magnet. I know the additives are not ferrous but I'm aware that there are some other non-ferrous minerals which are attracted to magnets, but I'm not sure which one's they are or if they are used as additives. I've also seen concerns posted about magnets interfering with bypass valves but generally the replies suggest that should not be a problem (12).

Any other thoughts on this topic? I appologise for the length of this post...there was a lot of data out there.

1. http://www.bobistheoilguy.com/forums/ubb...985#Post1611773
2. http://www.bobistheoilguy.com/forums/ubb...287#Post1326372
3. http://www.bobistheoilguy.com/forums/ubb...true#Post343975
4. http://www.bobistheoilguy.com/forums/ubb...true#Post343979
5. http://www.bobistheoilguy.com/forums/ubb...true#Post343981
6. http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=343972&page=2
7. http://www.bobistheoilguy.com/forums/ubb...ge=2#Post343989
8. http://www.bobistheoilguy.com/forums/ubb...true#Post343986
9. http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1284839#Post1284806
10. http://www.bobistheoilguy.com/forums/ubb...rue#Post1284862
11. http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1284839#Post1296303
12. http://www.bobistheoilguy.com/forums/ubb...786#Post1670786

 

[d00df00d]

Do any OEMs use magnets anywhere in the oil system for such a purpose? That would be an interesting piece of the puzzle IMO.

 

[PT1]

Toyota uses magnets in their transmissions in the pan. They instruct you to remove the pan to clean them and replace if weak in the service manual. My 4Runner has 2.The Lexus ES350 has 2 as well. The rear diff has a magnetic drain plug. My Harley has magnetic drain plugs in the engine, transmission & primary chaincase. All remove metal from the system.

 

[1 SX]

When i removed the transmission fluid pan on the taurus, there was a magnet in it. Also, there was one on my Saturns transmission filter...

So, magnets must do something.

I think with a high efficiency oil filter, there should be nothing to worry about about, in terms of engine wear and such. We all know there are cars out there with 300K miles, and the engines still run decent.

 

[ThirdeYe]

When I bought a new drain plug for my mom's Malibu it came with a magnet on the end, straight from the dealership (OEM part). The one that came with the car didn't have it however... weird, eh?

My transmission has one because it doesn't have a filter...

 

[rclint]

ThirdeYe made a great point. "My transmission has one because it doesn't have a filter.."

You will notice many of the magnets are installed by OEM where there is no filter. Magnetic drain plugs may be just a way to give a visual of the inside by use of magnet of drain plugs. I'm on the fence as well, if magnets showed any improvement I would think magnets would be equipped from the manufacture all through the engine, maybe even a specialized magnetic oil filter separate from the regular oil filter.

 

[Jim Allen]

When I pulled the trans pan on my 10K mile F-150 the magnet within it was bristling with metal. DItto the rear axle magnet.

Enginewise, I think things are less clear. I am totally convinced there are small, ferrous particle in the oil, too small to be captured by most oil filters, that could be captured by the right magnetic device. Since iron is one of the more destructive contaminants, it makes sense to get all you can out of the oil. BUT, we could get into the area of diminished returns here given how good some of the newer oil filters are, so I don't think it's a "once size fits all" proposition. It would make the most sense for an engine known to toss off lots of iron and for which a high efficiency oil filter is not available, nor a low cost bypass. Speaking of which, a good 1 micron bypass could do much the same thing as a magnet and get ALL the small stuff, not just the iron. I guess it would depend a lot on the cost of the magnetic device relative to it's KNOWN or PROVEN effectiveness, vs the cost of the other methods (such as a simply using a higher efficiency oil fitler) or even more simply, doing nothing abut scheduled service with a quality oil and filter and still having the engine outlast the car.

FYI, I recently had a particle count (optical) done on an oil sample from my 8200 hour diesel tractor, before (on 45 hour oil) and 50 plus hours after I installed a Magnefilter. The results were somewhat anomalous in that small particles (those much smaller than the oil filter can catch) drastically decreased and larger ones (plenty large enough for the filter to have caught) increased. I am asking to have those samples retested. I must point out that this was not a ferrographic test, so we don't know exactly the nature of all those particles. The oil part of the test showed low wear metals (especially considering it was a 2 year/98 hour run on a very tired old tractor), so my suspicion is that the Magnefilter did it's job. Eventually, I'll publish those tests here at BITOG.

 

[EricF]

my Firebird 700r4 tranny pan had a magnet, and a spot specifically for where they wanted it to go. I added another on the other end of the pan.
my taurus pan did NOT have a magnet, but I think the person who serviced it last took it out and probably kept it for himself.

I now have 2 magnets in the pan.

 

[defektes]

Originally Posted By: d00df00d
Do any OEMs use magnets anywhere in the oil system for such a purpose? That would be an interesting piece of the puzzle IMO.


Alot of my GMs have magnets on back of the plug its self. Usually some gunk on it.

 

[[RT] ProjUltraZ]

good post Daniel, i look forward to your conclusions based on the responses. i have a filter mag on the filter, and this one on the pan http://www.kjmagnetics.com/proddetail.asp?prod=BY0X06-N52 near the drain plug that is also magnetic.

i pull the magnets before draining hot to sweep it out. on my drainplug, i usually see some silver paste but not a lot. haven't done any UOAs since i started using these

Now that i think of it, i'll try sticking a q-tip into the drain hole after it's done to see what's on the pan above the big magnet. next oci

 

[mechtech2]

Well, a magnet in the crankcase won't ADD contaminants. It will only gather some iron/steel particles - a little or a lot.

A drain plug with a magnet in it makes it possible to clean it, and get particles out of the engine.

Stick one the side of the filter? Sure. It has to do something.

 

[Steve S]

Magnetic drain plugs can't hurt and probably will help.

 

[DanielinTheLions]

Thanks!

It seems to me that as long as you drain the oil with the engine hot that should help to get most of the particles out since the heat would help to reduce any residual magnetic force. I like the idea of checking the area above the magnet with a q-tip. That seems like a reasonable way to determine if any particles are remaining in that area after the magnet is removed. I'd be interested to hear your results.

 

[JHZR2]

That is a great overview - nice job.

Ive seen plenty of magnets in drivetrain components, most likely due to the fact that often (e.g. diffs, MTs, etc.) there are no filters.

GM did away with magnets on their engine drain plugs sometime between 98 and 04, or so it seems to me...

 

[demarpaint]

Originally Posted By: JHZR2
GM did away with magnets on their engine drain plugs sometime between 98 and 04, or so it seems to me...


Not bashing GM here, but it was probably a cost cutting effort. Those nickles and dimes do add up.

 

[cchase]

Originally Posted By: JHZR2
That is a great overview - nice job.

Ive seen plenty of magnets in drivetrain components, most likely due to the fact that often (e.g. diffs, MTs, etc.) there are no filters.

GM did away with magnets on their engine drain plugs sometime between 98 and 04, or so it seems to me...


My fathers 2006 Sierra 2500HD with 6.0 V8 has a magnetic drain plug.
My 2006 Pontiac GTO with 6.0 V8 does not have a magnetic drain plug.

The only thing I can think of is that GM figured the magnetic drain plug wasn't as valuable with my aluminum block/head engine and might be more useful on my fathers iron block engine.

 

[[RT] ProjUltraZ]

but the wear parts are steel

 

[skibender]

What pore size do oil filters filter down too?

 

[endeavor to persevere]

My 05 GMC Sierra has a magnetic drain plug in the oil pan. My Mag-Hytec trans pan and diff cover have magnetic drain plugs. The diff cover holds almost 4 quarts and has a dip stick. I have been using a rap a round magnet on my oil filter for the last 4 years. Thats probably why I hardly ever find any thing on the drain plug magnet.

 

[bigmike]

My 06 Silverado has one as well. I've used hard drive magnets for the past few years on my filters. I don't anticipate any issues arising from doing so.

I congratulate the OP for such a summary and condensing the debate down. I know that must have taken quite a bit of time to do so.