Magnetic Oil Drain Plate

For years I have replaced my oil drain screen with the magnetic plate seen in this picture. pic

Gene Berg used to sell cow magnets to attach to the oil pick up tube, and it worked well. I put these on my engines from the first day I built them. I understood what Gene’s principle was on this device, and used them for years. For the folks that don’t understand the difference between the screen and the magnet let me explain.

First of all, for its time the screen worked ok, but was lacking in two areas. It only caught the large pieces of loose material circulating in the oil. If you are maintaining your engine properly, changing the oil about every 4,000 miles and not letting crap get into the engine through missing oil caps and such, this is the best way to extend the life of your engine.

Let’s think about the wear your engine is subject to. Almost all of the micro wear particles are of ferrous metal. This occurs when the rings slide up and down in the cylinders. The rings and cylinders are made of ferrous metal, thus magnetic. It is for the most part, about 5-8 microns in size. It gets into the oil cooler, as well as the insides of the case itself and builds up.

If you have opened up some of these cases like I have, you will also see what happens when the oil is not changed enough. This wear material looks like cocoa powder, and adheres to the insides of the heads, as well as oil passages. The stock oil screen stops none of this material from going to the bearings. It is too fine to be stopped by the screen – end of story. This is another reason why it is critical to mind the miles for good oil change management for your air-cooled VW engine.

When you put a rare earth magnet flat (see picture), on the inside of a solid drain plate, the oil has to pass over it before it can go up the oil pick-up tube and into the oil galley to the bearings. The rare earth magnet removes almost all of the ferrous material from the oil on each pass over the plate. If you are running a high volume oil pump, it cleans the oil more frequently per trip.

With today’s technology, rare earth magnets that are flat enough to be placed on the inside of the oil drain plate. This does away with the cow magnet and the clamp attaching it to the oil pickup tube.

I’ve learned this is especially valuable on newly rebuilt engines that are breaking in a set of new rings. It will also catch anything ferrous floating around inside that shouldn’t be there. I’ve had friends tell how they have installed this drain plate set up on older engines, and have caught everything from 10mm nuts, to wrist pin snap rings. On older engines it will start cleaning up what’s in there, and may extend the life of the engine.

It can also warn you about something that may be going wrong, such as chunks of ring material that have broken off on a tired engine. Seeing this just may allow you to save the case on a rebuild.

Also, on cold mornings in northern climates the oil screen doesn’t let the thick oil go through as well. This can create some oil starvation, especially on the first few turns in the mornings. That is why some oil lights will flicker on until the oil warms up some. I noticed this when we lived in Bismarck, ND.

What this system won’t do is fix poor maintenance habits, protect against damage from lugging the engine, nor will it filter out non-ferrous crap like RTV sealant.

This is covered more extensively on Engines and Engine rebuild, but it’s important enough to mention here. I never use RTV on any of my engines. RTV can get into the oil passages and plug them up. On case halves you can use Gasgacinch. I use a product called Yamabond #4. This is for Yamaha motorcycle engines. These put out unbelievably high rpms, along with case pressures the VW never dreamed of. The product is thin, and when used sparingly on the case halves does a perfect job, ending leaks.

Here is what you need for this set up:

  • A flat oil drain plate without the removable plug in the center.
  • A flat rare earth magnet – you can get a rare earth magnet from a friends old disc drive – or the local computer repair shop may have them. Use the thin one – if you use just any flat magnet it may be too thick and restrict flow. You want about 3/4 of an inch clearance (see picture below).
  • Put it on the plate as seen in my picture (below). It also shows how the oil goes over the magnet prior to going to the main bearings – a good thing.
  • When you change the oil, use both of the gaskets in the oil drain kit.


That’s all . Use good oil (I like Chevron Delo 400 15w40). This is what I have used for years, and works for me. I have more than 65 engines running around with them inside. If you prefer something else, that’s okay.

– Mike Humeston