Are magnets for an oil filter and a magnetic drain plug a waste of money?

[oil pan 4]

I'd think strong magnets trap ferrous particles less than 25u too. If you look at the typical "black paste" collected on a magnetic drain plug, most of that debris has to be smaller than 25u. A lot of that debris is probably what can be detected by an ICP type UOA as iron in ppm. I'd think that magnets taking out iron would help reduce the reported ppm of iron in a UOA.

Here's an interesting post. The link to the study is broken now. But the conclusion was mostly composed of particles under 10u.
https://bobistheoilguy.com/forums/threads/effect-of-a-magnetic-drain-plug.130432/post-1867462

Also ...
https://bobistheoilguy.com/forums/threads/effect-of-a-magnetic-drain-plug.130432/post-1868711

I'm sure it does trap all sizes but have you seen garage54 see through oil pan videos? That oil moves around a lot more than I thought I would. Particles smaller than 25 microns probably just get washed away when the oil was on the move in that test.
Either way it's at least catching 25 microns and best case scenario where the drain is in a calm spot in the oil pan and they're using a better magnet it can be 10 micron.
Sound like good vs better to me.

 

[vwmaniaman]

They have magnet in the transmission pan and magnets in the diff. Why would you not want one on the oil drain plug?

 

[ZeeOSix]

I've put a good magnetic drain plug in every vehicle I've owned in the last 20 years. Install it at the first oil change, which is done at 500-600 miles on motorcycles and around 1000 miles on cars/trucks. On the subsequent oil changes, there's a lot of "black paste" on the magnet from the on-going break-in wear. As the engines break-in, the amount of black paste goes down substantially.

Here's the drain plug at an oil change done at 5K miles (4K OCI). Used in a 4.0L V6 Tacoma.

Here's the same drain plug at an oil change done at 50K miles (4K OCI).

 

[Mewbs]

I put Samarium Cobalt disc magnets on a filter baseplate (if space and clearance permits) in conjunction with magnetic drainplug on the sump. They do catch stuff, specially very fine particles. Probably overkill for most though having experience with industrial filtration systems which do use magnetic filtration along with traditional spin-on filters. Its a positive addition than something detrimental.

Of course it goes without saying you get what you pay for. Make sure the drain plug you are getting is not aluminum with cheap grade neodymium magnets. You want a high temperature grade magnet to match your operating conditions and temperature.

 

[Carlostrece]

Is anyone concerned that a strong magnet on outside of oil filter might interfer with the internal functionality of the filter? The filter's valve spring is steel. On some filters it's a coil spring. Would that spring it be attracted to the filtermag? Could that be detrimental?

 

[MetalSlug]

Only for a vehicles that you are plan to keep forever . For daily and change to new vehicles every 5+ years , no need.

 

[MetalSlug]

Gold Plugs are steel, so if the magnet does happen to become loose it will try to remain on the plug. Some cheaper magnetic drain plugs are aluminum.

Good to know, i just bought my first magnetic plug, and it happen to be gold plug

 

[k1xv]

They are cheap, and won't hurt the car. And you will feel better that you did something positive.

 

[ltslimjim]

Is anyone concerned that a strong magnet on outside of oil filter might interfer with the internal functionality of the filter? The filter's valve spring is steel. On some filters it's a coil spring. Would that spring it be attracted to the filtermag? Could that be detrimental?

Maybe if the magnet was placed onto the valve, but it's not. I use filtermags. They attach to the side of the canister; it sits halfway between the base and the dome end. It's not close enough to the bypass to do anything.

 

[Sumboodie]

I normally just see magnets on stuff without a filter or a not great filter.

Like hydraulic or trans filter "mesh" in older CATs that's got a bunch of magnets. The mesh keeps the big stuff out.

 

[Carlostrece]

Maybe if the magnet was placed onto the valve, but it's not. I use filtermags. They attach to the side of the canister; it sits halfway between the base and the dome end. It's not close enough to the bypass to do anything.

OK.

 

[Fattylocks]

I think that they are a lot of fun if nothing else so not a waste of money to me.

 

[Hohn]

I think they are worthwhile because it's not like you are buying them every week. Drain plugs are not the thing to save money on. Eating out is.

The amount of wear metal on my Transmission drain plug (on my van) was almost scary. But imagine the worse outcome of having that metal still floating around in the oil with no filter (Honda trans).

I think magnets are in that "do no harm, why not?" kind of thing. Will it make your engine last longer? Doubtful. Will it give you a good visual reference of any ferrous wear particles? Probably.

It's probably good to have a magnetic plug to assess how well your filter is filtering. Ideally the plug would have zero dust on it, but whatever does accrue should be well under 10 micron particles. The kind that would show up in UOA. So if you have a clean magnetic plug AND a really good UOA result, that bodes very well, IMO.

 

[Zee09]

To a top extractor the drain plug isn't required... filter magnets are different. I personally wouldn't bother with 4k changes

 

[crashz]

They have magnet in the transmission pan and magnets in the diff. Why would you not want one on the oil drain plug?

My sentiment as well. Different applications, but I like having a magnetic drain plug. Sort of a quick condition assessment too. If I see a change in the drain plug catch, I know I should open the filter and take a peak.

 

[dubber09]

IMHO, magnetic plug is not waste of money, magnets on filter may cause problems thou.

 

[ZeeOSix]

Two advantages of a magnetic drain plug: 1) It does catch ferrous particles the filter can't, and those particles can cause wear, 2) It's a way to monitor if anything abnormal is going on with ferrous parts chewing themselves up. Especially good to have on motorcycles that also share the oil for transmission lubrication.

 

[Olds394]

Absolutely they help.

Here is an unconventional way in which a retrofitted magnetic drain plug helped - it caught the debris from a bad repair.

Thread 'Volvo dealer used abrasive wheel to clean engine sump'
https://bobistheoilguy.com/forums/t...d-abrasive-wheel-to-clean-engine-sump.374594/

With out the plug, I might not have known.

Plus if it’s a magnetic drain plug, you don’t have to cut the oil filter every time.

 

[EvoMan]

Plus if it’s a magnetic drain plug, you don’t have to cut the oil filter every time.

Not cut open an oil filter…….blasphemy

 

[ltslimjim]

IMHO, magnetic plug is not waste of money, magnets on filter may cause problems thou.

What kind of problems using on an oil filter? Randomly place magnets? Sure. Designed filter magnets? I don’t see an issue.

We had a member @harry j that went 649k miles on the original engine of a 93 Civic and they used industrial grade oil filter magnets. We’re talking $600 pairs lol. Didn’t seem to cause any harm there. They have a backing that is shielded so that magnetization is only towards the oil filter canister itself.