The Original, don’t be fooled by the cheap copies.
We have developed a caterpillar filter for an Allison transmission. On 10-Jun-18 we started out with 67,000 miles on the fluid when we changed the stock filter out for a Caterpillar fuel filter, its one of the best filters that Caterpillar makes. The filter is a sub 4 microns with synthetic media and flows 10 liters per min. We took a sample of the fluid when we changed the filter and 30 miles after. What we noticed in the second sample the results were impressive for only 30 miles. A lot of particle counts were lowered and we got a cleanliness rating of 16/15, down from 21/18. Which is from a poor rating to a very good rating.
So I took one another sample after about 2000 miles. (13-Jul-18) Now the filter is a sub 4 micron filter, so technically anything under 4 microns can go through the filter. I think that’s what we are seeing in the 4 & 6 micron particle count, but through the rest of the sample, Copper, iron, aluminum, lead, silicon, sodium and potassium are down if not removed. Particle counts over 10 microns are drastically reduced compared to the 1st sample. So does our filter work, I’m thinking so.
Note. We are using a Filtermag on our filter not the donut magnet that comes with the transmission, we wanted to turn the whole filter into a magnet.
What next, well at 206536 miles, we changed the transmission fluid and filter along with the engine oil and Cat oil filter, and started our quest for 20,000 mile oil change testing every 5000 miles. We got back from the lab 2 samples, the first is the latest transmission sample. With just about 8,000 miles on the new filter it's just starting to show signs of bypassing the filter. I'm not worried because of the amount of miles and dirt in the fluid before we put the filter on. We had 68,000 miles on the fluid when we started this test, ran it for another 8,000 miles to see just where the fluid would clean up.
To be perfectly honest I'm quite impressed. I had planned on changing the fluid before the test but I really wanted to just see how much the fluid would clean up. I spoke to Caterpillar and we discussed filter options, but we didn't come up with any other options. The choices are the Advanced filtration with cellulose paper or the Ultra filtration with synthetic media, the synthetic being able to hold almost twice the capacity of the cellulose. I have come to the conclusion that when I release the adapter I will include 2 filters. Since most people won't flush the transmission, the first filter is cellulose for the first 2,000 miles to clean the transmission fluid. With a drain and fill you only replace 1/2 of the dirty fluid, so the fluid still needs to be cleaner. The second is the Ultra filter to run the remainder of the time between filter changes.
That brings up the filter change interval, right now we are shooting for 20,000 miles on a Ultra filter change. If you wanted to use the Cellulose filter only, you might want to change the filter around 10,000 miles. Just to be sure we are testing the transmission fluid each month till we have a more definite filter change interval.
Its March 1st, we had the transmission filter adapter in the CNC shop for evaluation and to turn it into a 3d model, we have not been able to test it further. But today or tomorrow we will replace the stock filter and use the Caterpillar filter and start testing again. We have about 11,000 miles on the stock filter and a fluid change. Now we are using Royal Purple ATF so I'm really curious to see where the fluid is now.