- Joined
- Sep 26, 2010
- Messages
- 9,807
We have likely discussed this ad nauseam (or not), but one cannot help but wonder why the size range in UOA tests is not extended or has a separate stage for at least two size ranges of particles. Case in point, when I drained the factory oil from my GLC, it was very pearlescent when swirled in the sun. This indicates to me there is a considerable amount of metal which was not trapped by the oil filter. For clarity, I have witnessed this scenario with every vehicle I have ever owned so it is not unique to my GLC.
I will assume that factory Mercedes-Benz oil filters have efficiency ratings inline with most other OEM filters, perhaps something on the order of 90% @ 30-40um. A further assumption is the particles that I saw in the oil are too small to be trapped by the filter, but equally too small (or too large) to be picked up by the UOA test—else the PPM quantities would be higher for the wear metals in the test results.
Based on the above, I have three questions for thought:
1. Do you agree or disagree there is more metal in the oil than the tests reveal?
2. Do you think the metal is too small to cause wear thus the current particle size range is sufficient?
3. Do you think changing the UOA test results to capture the quantities of the particles obviously present in the oil would be of value?
I will assume that factory Mercedes-Benz oil filters have efficiency ratings inline with most other OEM filters, perhaps something on the order of 90% @ 30-40um. A further assumption is the particles that I saw in the oil are too small to be trapped by the filter, but equally too small (or too large) to be picked up by the UOA test—else the PPM quantities would be higher for the wear metals in the test results.
Based on the above, I have three questions for thought:
1. Do you agree or disagree there is more metal in the oil than the tests reveal?
2. Do you think the metal is too small to cause wear thus the current particle size range is sufficient?
3. Do you think changing the UOA test results to capture the quantities of the particles obviously present in the oil would be of value?