Do magnetic crankcase drain plugs make any difference?

[wwillson]

I installed this drain plug with a neodymium magnet a couple oil changes ago. I have no evidence that they help anything but don't see how they could hurt.

Until now I have never had any way to see if they would catch metal that was in the oils. If you have followed my Durango roller rocker failure, you know that the last oil filter I pulled had an enormous amount of ferrous (able to stick to a magnet) metal.

Thread about metal in oil filter: https://bobistheoilguy.com/forums/t...al-likely-bad-rocker-chewing-up-a-cam.399622/

Picture of the oil filter with metal:

I changed the engine oil in the Durango today. This is what the drain plug looked like after 24,000 miles and a bad rocker:

Yes it did catch some metal, but I expected to see more because we know there was a lot of metal available to be caught.

After seeing how little metal this magnet caught, my opinion is the drain plug magnets are pretty much a waste of money.

 

[AZjeff]

Use it for 24k miles without a failing part and see if it catches as much fine material. Would particles that small suspended in oil be harmful?

 

[SC Maintenance]

Are you sure the wear metal is ferrous? Most of it was from the roller which was likely stainless correct?

Still, looks like a fair bit of waste it picked up?

 

[wwillson]

Are you sure the wear metal is ferrous? Most of it was from the roller which was likely stainless correct?

Still, looks like a fair bit of waste it picked up?

The metal in the filter sticks to a magnet, so yes it's ferrous. The metal was from the axle, roller and needle bearings.

 

[Owen Lucas]

Use it for 24k miles without a failing part and see if it catches as much fine material. Would particles that small suspended in oil be harmful?

From what i've read on here, by capturing ferrous metals, oil oxidation is reduced, but the effect is probably marginal. Cheap insurance though for putting a tiny magnet on a drain plug or oil filter. Maybe it can make a difference over 100k miles?

On the other hand, these tiny particles that get past the filter and get caught by the magnet, they would likely be causing abrasion if enough of them are floating around as filters don't usually catch anything below 20 - 25 microns and the oil film on bearings is usually 1 - 10 microns.

 

[Furious]

My 4.3 Chevy comes factory with a magnetic drain plug, it never has metal on it.

Let's be realistic, how many cars out there have 200,000 or even 300,000+ miles without magnetic drain plugs or magnets on oil filters just running typical cheap oil filters or OEM oil filters with not the best efficiency?.

Answer, too many to count.

With properly maintained vehicles that are already broken in magnetic drain plugs really do not make any difference at all. If it comes with a magnetic drain plug from the factory you might as well keep it, if it does not there is no point in switching.

 

[twX]

I'd expect that only a small percentage of the metal bits will pass close enough to the magnet to be captured by it before they get sucked up into the pickup. Magnets at the base of an oil filter will do a better job, since the metal bits will need to pass close to them, but does it really matter if the filter will catch them anyway?

The type of metal you want a magnet to pick up is the 2 to 40 micron particles that you can't see. These can get through the filter media and cause wear. The big bits don't matter since they'll all be filtered (as long as the filter isn't bypassing).

 

[Japanese]

This is what the drain plug looked like after 24,000 miles

Maybe would caught double or triple that if the oil was changed a couple times in between.

 

[GW.]

Perhaps the drain plug caught what the filter couldn’t. They work well together.

 

[JHZR2]

It’s a good thought exercise.

My MB diesels don’t come with them, and they’re far longer lived engines than most.

In fact, only my GM product came stock with one.

I tend to retrofit magnetic plugs. To me it’s peace of mind. And I’m not so sure that granular metal is a fair comparison.

First, it’s big enough to get trapped in the filter.

Second, because of size and well-mixed flow in the oil pan, I suspect it has too much momentum to get snapped by such a small magnetic surface, and too heavy to be mobile in the oil when at rest.

The picture of what the plug collected looks like a decent amount more metal than I usually see, though your oci may be longer. The only thing that really surprises me is that it doesn’t look like a single granule collected in the plug. I’d have expected to see one/a few.

To me it is still good insurance to get whatever can be taken out, out. Why wouldn’t we want to get the oil cleaner, even if just a few grams of fines?

 

[f355spider]

Never used one. I have a BMW and a Toyota Tundra owned since new...both are just shy of 400k miles each. Just did an oil change today on the Tundra...it's showing 393,400 miles. Use one if it makes you feel better...

 

[50yr Street Mech]

I have yet to own a vehicle with a magnetic oil plug. Magnetic transmission / differential plug ,,,,yes. They've all gone plenty of miles without it. But, if it makes you happy, by all means use it.

 

[SC Maintenance]

The metal in the filter sticks to a magnet, so yes it's ferrous. The metal was from the axle, roller and needle bearings.

Well still some > None. I guess its up to the owner to decide if the juice is worth the squeeze.

Was there lots of glitter in the pan as well?

 

[rstsco]

I bought one to install during the next oil change. We'll see what we see after the next OCI.

 

[BobsArmory]

I think of them as a window looking into the general health of the engine. I don't expect mine to save my engine.

 

[Dutchy491]

Magnetic drain plugs are quite beneficial in applications that don’t have a filter, like vehicle differentials or especially in small engine drain plugs….
My Toyota Tacomas came stock with them in the driveline.

 

[Inked]

I use one on each of the cars as well as one on a WEN generator without a filter. I don’t however, come close to Wade’s mileage between oil changes though which led me to wonder about the limitations (volume/mass) of the magnetic attraction forces of these magnets. Just as filters reach their capacity and go in to bypass, pondering how effective these magnets remain after a relatively large accumulation of these ferrous particles become attached.

 

[ka9mnx]

I've always felt magnetic drain plugs and filter magnets were a cash grab. On an axle pumpkin, that might be a different story.

 

[wwillson]

Was there lots of glitter in the pan as well?

There is no way to see in the engine oil pan without removing it and I'm not going to do that.

 

[joekingcorvette]

I seen a magnetic drain plug one time with some needle type bearings stuck to it. I believe at one time there must have been some upper engine damage on an LS engine I had. The vehicle ran great but at some point in time those bearings made it to the bottom of the oil pan. It was on a 97 Corvette.