SR56
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Quote:
BearGator56,
There is a perception that FF filters can't remove soot particles, since they are soo small. This is technically true, if in fact these are discrete particles and not masses of soot that have clumped together. What happens is that once the soot has reached a certain concentration, the soot starts to clump or agglomerate, due to electrostatic attraction. Once that occurs, these clumped particles can and will be removed by the oil filter.
There is actually a controlled test that is part of the API, CI-4+ and CJ-4 specifications that evaluates the ability of an engine oil to minimize filter plugging. As I recall, the limit of this test is when you reach 79 psid (pressure differential), across the filter media. In other words, this is a severe overtest.
PAO basestocks generally do a superior job of suspending/dispersing soot. This is true even if they have the exact same additive chemistry as a petroleum lubricant.
So using a low viscosity, 5w-30, PAO/Ester synthetic is going to get you the best results under these conditions. I suspect a 15w-40 petroleum lube would be a 20w-50 or 25w-50 with these soot levels you're seeing and the truck would not start easily in cold weather.
If you have time, I'd cut the 7500 mile filter open; spread out the pleats and look for signs of clumped soot particles. Wash it out with some mineral spirits if you have to ....
The oil I use is Amsoil's Series 3000 Heavy Duty Diesel 5w30. I will grab another oil sample at 7500 miles (and change the filter), and post it. Not sure how long it will take for the soot to work itself out from the blown injector. As long as I can get another 30,000 miles off of this oil, I think I'll be fine for a while. I'm hoping to get well over 50k on a change, though.