Magnets in Oil Filtration, Other Oil Analysis Methods

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Jan 9, 2005
Sarasota, Florida
I have for some time been interested in the use of magnets to augment oil filtration. I am generally a Doubting Thomas and want to see proof of things so I called the president of Fluid Rx to find out about their Magna-Guard product. I received several products to test and reading material. Several SAE papers were referenced: 8881827- Review of Lubricant Contamination and Diesel Engine Wear, Needelman and Madhaven, and 881825 - Correlating Lube Oil Filtration Efficiencies with Engine Wear, Staley (GM). Both are from the Truck and Bus meeting, Indianapolis, IN, 1988. They also quoted a later paper - 991927 - Review of Lubricant Contamination and Diesel Engine Wear (author(s) not listed). All papers included a host of additional references.

All these references are old but certainly hold true. Maybe there are few new papers as we already know all there is to know about filtration and it’s usefulness. One recurring theme is that the concentration of particles, particularly in the 0 - 20u range cause the most wear. This was brought out in the latest SAE handbook as well. Particles 30u to 80u and more cause wear but actually less than a higher concentration of smaller particles.

The problem with filtration is, well, filtration. The filter gets clogged, the pressure drop through the filter increases and eventually the filter is just bypassed altogether. There has to be a happy middle ground where there is some filtering but not too much. The use of magnets is certainly helpful. Just look at any transmission or differential magnetic drain plug.

I had several questions for the president of the company. 1- What was the reduction of oil flow as this magnet they sell is placed into the oil filter itself? (It must be a metal spin on filter). He showed another paper that shows an average pressure drop of 0.4 PSI at an oil flow rate of 8 GPM (separate paper). This is certainly acceptable. 2 - Why is not everybody using this? He said people were slow to accept this concept but that several large trucking companies (his major sales) have been using them for years. He has simply not gone for a national advertising campaign. ?Maybe he makes enough money? I see no reason not to use these magnets.

Several endorsements were quoted:
Motor Trend, Nov., 1999, Aftermarket Business, Feb., 2000, PowerLine, NYT and others.

Now, having endorsed their use I will say that every car I own will get them. I have not figured out how to use them in the MB’s (SL600 and Maybach) where the filter is just a paper? glass? element and the cover is aluminum. I will figure it out.

One thing complicates the effort to quantitate their benefit. If your gas mileage slowly increases as iron containing particulates are removed then that would be a measurable criteria. When doing a UOA however, the iron (Fe) would be picked up by the magnet. If my engine had increased wear with that new 10 wt oil I was trying I may get an artificially low Fe level. On the other hand at least that Fe would not be circulating causing even more wear. It would seem that Cu, Pb and other metals would be high anyway in my failing engine. If the magnet was making the engine better with removal of all the circulating Fe particles then other wear particles would also have to go down. There would still be a reduction in Cu, Pb and others. Perhaps, with less wear and better lubrication the additives would last longer. This is actually a claim of the engineer. They say that oil change intervals may be doubled with the use of their magnets. (This I would have to see).

I think we should all try these things, give the data to the manufacturer and get published. Maybe something we do would benefit others in this way.

Other things that I have obtained are graduated filter paper tests for motor oil, gear lubes power steering fluid and other fluids. There are charts and pictures to compare. These are all inexpensive but standardized filter paper tests and with the aid of any UV light, particulate tests. Again, I see no down side to these products and I will incorporate them immediately.


aehaas, I'm way ahead of you...

I've been using a pair of hard drive magnets on the outside of my oil filters for quite some time now. They've stayed on fine through several brutal New England winters just by their sheer magnet attraction (they're wicked strong magnets). Some aftermarket oil filter magnets (Beartrap comes to mind) simply wrap around the oil filter, remain attached the same way.

My biggest worry was that the magnets would come loose or fall off in mid OCI, thus releasing a flood of ferrous particles into the oilstream... bad idea. Hasn't happened yet. I'm not worried about it happening now. An inline magentic trap should reduce this possibility to virtually nil.

One of these days, I'm going to cut open my oil filter and see how much (if any) ferrous particles are trapped by the magnetic field inside the filter. May be nothing. May be trace. May be a bunch.

Come end of September, I'll change my oil and filter, so I'll figure out how to cut open the filter without generating more ferrous particles and contaminating my experiment (I'm thinking chisel).

[ May 18, 2005, 03:20 PM: Message edited by: bigpaulo ]
Help me understand. The idea here is to achieve the same benefit often advertized by bypass filter marketers without the extra hardware and plumbing of the bypass filter, right? Except, of course, that these would only work to remove iron where a bypass filter would remove everything within its filtration-size range. Are these magnets supposed to filter sub-micronic particles?
I have just started using a SuperPlug "oil drain plug" and a FilterMag which wraps halfway around the oil filter as of my last oil change 5 months ago and will soon change my oil and do a UOA.
My thoughts on the magnets for oil filters: the magnet better be very strong, like a rare earth Neodymium magnet. I have a couple nice curved Nd ones.....and one time when I cut open a used oil filter, and on the inside I could see just the faintest outline of where the magnet was. The outline wasn't piles of iron - more like heat witness marks.

I have an oil plug magnet and never see any iron on it
even after 10,000 miles.

Yes - a real study is in order.
Mazda, for a time, had magnetic drain plugs on the crankcase drain. I don't think they use them now though. Many manufacturers use magnetic drain plugs for manual transmissions where filters aren't used.

I think magnets for crankcase filtering use would have very limited benefits. First, they won't attract silicon, which is the hardest and most damaging contaminant by far. Second, iron doesn't exactly plug up an oil filter in a normally wearing engine. Oxidation byproducts plug the filter, and the magnet won't attract them either. Third, the oil filter will trap most of the damaging iron particles.

I think magnets for crankcase filtering use would have very limited benefits

I basically agree the benefit is small, but an exterior magnet is relatively cheap, lasts a long, long time, is easy to do, etc.

While the magnet is limited in what it can pick up, and the biggest particles are supposed to be trapped by the filter, I figure that any small stuff it keeps from circulating is good, even if the difference is probably not measureable. Its just that much less material floating around acting like sandpaper or valve grinding compound.

For me, I just like the tinkering aspect, doing little things to help even if it is minor. But I don't expect any really noticeable difference other than I like doing those things. That is just part of the hobby aspect.
If you are interested in experiementing with magnets, I have to recommend:

Hard drive magnets (if you mean the drive motors) are not nearly as strong. The magnets you want to use out of a hard drive are the ones that control the movement of the head.

I've had one of those magnets stuck to my oil drain plug for about 8000 miles now, including one 30-40mph jump through a ditch. It destroyed my fog lights and knocked one tire off the rim. The crossmember made a nice little gouge in the ground where it hit, and the magnet actually hung down silghtly lower than that. All that happened to the magnet was that it was pushed up to the back of the oil pan instead of staying on the drain plug.

These magnets are NOT something to play with, if two snap together with your finger in the middle, you WILL get a blood blister.

That being said, I wouldn't own a car without at least one big one, or several smaller ones (like the ones in the ebay url above)
maybe we can use a filter full of bismuth to send the magnetic particles to the remote end of the filtration system.
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