magnetic oil dran plug

People aren't exactly bringing you good engines to rebuild? Reel it in a little.
YOU presume you know me! :cautious:

Well first of all YES many of my customers DID bring me their undamaged engines to rebuild. My shop was a Performance Engine Machine shop. So ya many were racers and wanted the engines freshened up. I did get a "small" percentage of daily driver engine but that was not my main bread butter part of the business more of a curtesy for my customers I built their Race engines for and there friends and family . And here is something else, they all got a "RING" magnet I attached to the bottom of their oil pan. That was in case they "smoked" one of my engines we could look into the exact cause. Naturally they also had a drain plug magnet as well. The RING magnet would just grab on the really large metal parts from a grenaded engine. :LOL:
 
I`m thinking about to get one for my bike as engine and trans share same oil and naturaly more shavings will be in the oil. But is there any point putting same plug on a car? It depends. Many engines use aluminium pistons and skirts, bearings are made of copper or something like that. Any shavings from those parts a magnetic plug won`t pick up.
 
Last edited:
They are best viewed as another diagnostic tool telling a part of overall engine condition; read what they are catching understanding that it is only ferrous metal.

I have had a two saves by them though, one was ages ago on a higher mileage BMW 2002 that started making metal. Turned out to be a timing chain issue that was repaired and the engine soldiered on, the other was when the tip of a piston oil jet fell off. This was on the newly rebuilt engine in my '84 diesel Rover. The tip was attached to the magnet. Would I have noticed otherwise??? Who knows. I replaced the oil squirters.
 
Heres an example of what you occasionally find on a mag drain plug - these would be needle bearings from a rocker assembly.




Screen Shot 2021-09-30 at 8.34.39 AM.jpg
 
These threads like many when I see members posting in the opposing with comments like "I don't use "X" and have never had an issue"... I think until they do? :LOL:
Drain plug magnetic and other magnets in various locations in either a engine rear end or transmission are simply a inexpensive insurance that should something happen it may save an engine or transmission.
 
I have a 2021 Honda HRV Sport with the 1.8. I will be doing my first oil change on this in a few months. I was thinking of replacing the oil drain plug with a magnetic type. Any thoughts about this...good or bad...
I have used magnetic plugs for yeas on about 6 different vehicles. Some of them were cheap auto parts store drain plugs and others (currently) were fancier ones with rare earth magnets. Current ones are the gold plugs and it seems fine. Above it's mentioned that a " The Gold Star plug lost a lot of its strength.".... I don't know if that is the same as what I have but I have not noticed any reduction in strength of my plug. However I did not measure it scientifically when I got it, currently, or when it is in use and hot. I have no practical way to do that.

I do know that when I remove them from the pans, they always immediately try to violenly stick to the pan (except in my volvo with an aluminum pan). The magnet is quite strong


Regardless, in all cases I have never noticed anything on the magnet other than a small amount of dark sludge which I'm sure is some metal plus oil. It's always a tiny bit .. I wipe it off .
Does it help? As other have said.. probably not. As others have said, it's a good diagnosis tools.

A little sludge.. engine is ok
Actual slivers? oh boy.

btw. when I say sludge here. I do not mean sludge as in a sludged up engine. I mean just a small blob of some oil/metal residue that is held to the magnet in a sludge like consistency. once off the magnet is just absorbs into a paper towel

-A
 
  • Like
Reactions: hrv
These threads like many when I see members posting in the opposing with comments like "I don't use "X" and have never had an issue"... I think until they do? :LOL:
Drain plug magnetic and other magnets in various locations in either a engine rear end or transmission are simply a inexpensive insurance that should something happen it may save an engine or transmission.

Nothing wrong with opposing point's of view, I've never personally seen a magnet SAVE a engine, transmission, or differential before.

Differentials make a lot of Ferris material, Especially during break-in, So I see the benefit of the magnet to get the metal out of suspension.

Automatic transmissions have magnets to keep Ferris material from building up on the solenoids which are electromagnetic. If a catastrophic failure occurs that produces a ton of metal, The magnet quickly loads up & becomes ineffective.
Sure....During break-in the Carrier Gearsets, Sun Gears, & Ring Gears will sluff off some Ferris material, It's wise to drop the pan & clean the magnet/s after 30,000 miles or so.

Engines have their lube oil changed far more often than differentials & transmissions, I just don't see much benefit in magnets. GM had quite a few models with magnetic tipped drain plugs......The longer the lube oil was ran.....The more material was on the magnet.

I'm sure you can agree that the number 1 & 2 causes of engine failure is Overheating & Running one out of oil, I'm not speaking of race engines of coarse.
 
Call me crazy, but I still think something as simple and cheap as a magnetized oil drain plug would be used by the factory if it offered real benefit. I have never seen one, but that doesn't mean there aren't any...
As @clinebarger mentioned, we see magnets in differentials and automatic transmission pans.

Just my 2 cents.
I do kinda like 'em though. Just too cheap to spring for one...
 
Nothing wrong with opposing point's of view, I've never personally seen a magnet SAVE a engine, transmission, or differential before.

Differentials make a lot of Ferris material, Especially during break-in, So I see the benefit of the magnet to get the metal out of suspension.

Automatic transmissions have magnets to keep Ferris material from building up on the solenoids which are electromagnetic. If a catastrophic failure occurs that produces a ton of metal, The magnet quickly loads up & becomes ineffective.
Sure....During break-in the Carrier Gearsets, Sun Gears, & Ring Gears will sluff off some Ferris material, It's wise to drop the pan & clean the magnet/s after 30,000 miles or so.

Engines have their lube oil changed far more often than differentials & transmissions, I just don't see much benefit in magnets. GM had quite a few models with magnetic tipped drain plugs......The longer the lube oil was ran.....The more material was on the magnet.

I'm sure you can agree that the number 1 & 2 causes of engine failure is Overheating & Running one out of oil, I'm not speaking of race engines of coarse

100% agree on major causes of failure, gears and most everything with you for that matter but we do diverge a little.

I had a magnet on my outdrive (factory puts in 2 ) loaded with metal during a routine oil change, and it prompted a removal and subsequent rebuild. I was hours away from a larger failure that would have wiped the drive totally. 4K would have turned into 10.
Im digging around for a picture

On a truck with a heavy duty towing cycle, DOHC and mile long timing chain - I want that oil as clean as I can get it.
 
I figure it cant hurt to catch ferrous metals before they hit the oil pump which is pre oil filter or before they accumulate on the pickup screen.
The amount caught depends on the strength of the magnet and even with a strong magnet how much is it really catching? That being said I wouldn't count on it to "save" the engine. If the engine is shedding a lot of metal a lot of damage has already been done. Six of one half a dozen of the other.
Like the oil pressure light, they should refer to it as your engine is blown light, it is there and it works but by the time you see it its all but over.
 
Nothing wrong with opposing point's of view, I've never personally seen a magnet SAVE a engine, transmission, or differential before.

Differentials make a lot of Ferris material, Especially during break-in, So I see the benefit of the magnet to get the metal out of suspension.

Automatic transmissions have magnets to keep Ferris material from building up on the solenoids which are electromagnetic. If a catastrophic failure occurs that produces a ton of metal, The magnet quickly loads up & becomes ineffective.
Sure....During break-in the Carrier Gearsets, Sun Gears, & Ring Gears will sluff off some Ferris material, It's wise to drop the pan & clean the magnet/s after 30,000 miles or so.

Engines have their lube oil changed far more often than differentials & transmissions, I just don't see much benefit in magnets. GM had quite a few models with magnetic tipped drain plugs......The longer the lube oil was ran.....The more material was on the magnet.

I'm sure you can agree that the number 1 & 2 causes of engine failure is Overheating & Running one out of oil, I'm not speaking of race engines of coarse.
You are missing a BIG point because a few of us actually deal with many engines and in my case I built engines in one of my business the use of a drain plug magnet is to 1) keep the oil as clean as possible, 2) if something is starting to go wrong many times seeing what is caught on the magnet can determine a plan of action on what to do to repair the problem, #) should a failure occur I can determine many times what was the cause by looking at the material caught on the magnet.

Oh and by the way any new engine ,transmission and differential will have material during break in. There are a few exception like a "BLUE PRINTED" engine of specialized mostly performance transmission and rear end builds.
This is also based on a few of use doing this for a living on dozens and dozens of builds...

I agree on your "guess" about the causes of engine failure with daily drivers but only on the heating not on the oil. In over 4 decades I can count on one hand how many engines failed because of oil and even that may be questionable. If a oil pump failures that would be counted someone that had a high mileage engine never checked or changed the oil(rare given the numbers of vehicles in US alone) but now on the internet we always will here about that GUY/Girl that run there engine for days with the oil l;ight on and .... bla bla bla.... Lol.
 
I figure it cant hurt to catch ferrous metals before they hit the oil pump which is pre oil filter or before they accumulate on the pickup screen.
The amount caught depends on the strength of the magnet and even with a strong magnet how much is it really catching? That being said I wouldn't count on it to "save" the engine. If the engine is shedding a lot of metal a lot of damage has already been done. Six of one half a dozen of the other.
Like the oil pressure light, they should refer to it as your engine is blown light, it is there and it works but by the time you see it its all but over.
I agree with all but, your last statement , you are suggesting the oil failed? It is a old MYTH that if the oil light comes on the engine is toast, you know that? It s the people that ignore the RED lights the same as the yellow lights. hahaha! Right!
Let my give an example.....
I am in a race end of the season I needed all my points win lose or draw, all I needed to do is simply make a pass . I run S/G 9.90. So I am idling and the oil pressure drops to 0psi and the engine light and oil light come on and then the engine safe relay kicked in and shut the engine off. But I restart and now I have oil pressure and everything is fine? I heat the tires in the burn out box and the same thing happened. I said "F" it I need to make the run for the points so I bypassed the safety and let the engine run. While idling waiting for the stager to wake his butt up and let us, me and the guy I was running against stage I watched the oil pressure return to normal 80psi????? And then drop to 0 psi????? So I stagged launched hard buzzed the engine to the usual 8500/145+mph and did my run expecting midway down the 1/4 the engine was totally going to grenade. As is idled back to the pit my oil pressure again came back up and then down again. I was sure I spun bearings and lost the oil pump or basically the whole engine. That's fine the engine gave me a complete no trouble up to that point season so it was going to come out and freshened or rebuilt anyway for the next year season. When I pulled the intake there it was the cause of the oil problem. I left a blue rag that I coved the valley when changing intakes after my last race a month previously. It was an all nighter to get ready for that race and I was tired so I never saw the rag when I installed the intake back on the engine. So when the oil was pumped up to the top end of the engine the rag prevented the oil to return normally and held much of the oil from the sump in the valley and head casting area. So the sump was almost pumped completely empty of oil which was sitting in the top end of the engine. LOL. DA! The only thing I surmised that saved the engine was simply the oil itself that remained on all the bearing surfaces and that the run was less then 10 seconds the oil did its job well.
 
Last edited:
These plugs are unnecessary. The only way to find out if they picked up anything is to remove them. The vast majority of vehicles don’t have them.


The point about transmissions and differentials is a good one. These will shed off far more ferrous material yet the vast majority of them never get the fluid changed.
 
Back
Top