Reprinted with permission from Donny Petersen, Heavy Duty Cycles, Toronto, Ontario.

HEAVY DUTY CYCLES Technical Article Section

Please read disclaimer at the end of this article, thank you.

Summer 2004

Oiling + Oil Filtration

1999-2004

Part III of III

This gets complicated before it gets simpler. This has been a real education for me. We will demonstrate that unfiltered oil re-circulates, sometimes many times over, through the engine belying the claim that no debris can be transferred from engine compartment to engine compartment. The three Twin Cam compartments are; timing chest, bottom end and the top end. In comparison the Evo had two compartments: the top end and bottom end.

We are going to answer 3 questions:

1. Does a Twin Cam 10-micron oil filter work better than a 30 micron Evo oil filter?

2. Do Evo and Twin Cam oil filters, filtrate out ALL particulate more than 30 and 10 microns respectively?

3. Thirdly and most importantly does all the oil go through the filter?

Now that we have looked at (in Parts I and II) where and how the oil is channelled in the Twin Cam engine we can now examine oil filtration as well as the movement of debris throughout the engine with normal wear as well as catastrophic breakdown in this last of 3 parts. Harley Davidson like many other manufacturers have started to inform the consumer about the improved filtering capacities of their oil filters. They do this on a superficial level, which is all most consumers want to know anyway, by indicating the micron ratings for the filters. Harley does not make its own filters or oil but vendors them out for the best all round bid subject to their specifications.

Micron Ratings

For an easy but inaccurate consumer understanding of a filter’s capabilities, a micron rating is sometimes given by individual companies like Harley to show the efficiency of their product.

A micron is a millionth of a meter or for those not metrically inclined 39 millionths of an inch. The micron rating leads the consumer to mistakenly surmise that any and all particulate above the micron size rating is filtered out of the oil. The rating given to the Evo filter is 30 microns and the Twin Cam is 10 microns. Therefore the consumer, myself included before writing this article, makes some simplistic feel-good misassumptions regarding engine protection and oil cleanliness. Manufacturers do their own micron rating tests. There is no industry standard to do this by so comparisons between manufacturers are tenuous at best. However, as we will see, this is not a biggie because the micron rating doesn’t impart as much information as it seems. According to Amsoil, which has a top reputation in my books, almost any filter can filter out some particulate as small as 1/10th of a micron. As we will continually see, micron ratings are not accurate. Filter manufacturers initially used micron ratings to evaluate the relating porosity of flat sheets of media used in making

Filter elements.

The purpose of showing the relative porosity of a sheet of filter media has been served well by the micron rating. However, the micron rating has been used as a measure of filtration efficiency, something for which it was not originally intended. Some of the reasons why a micron rating is totally inappropriate for this are

1. The test is not repeatable at different labs. Each manufacturer has its own test procedures. Although the test is a valid comparison of one filtering paper or media to another within a given facility, the micron rating cannot be reliably used to compare filters from different manufacturers. One manufacturer may give a filter material a micron rating of 10 while another may rate it 2 and a third may rate it 15.

2. There is no consistent relationship between micron ratings and actual filtration efficiency. The relative poros