I work for a large hospital as a maintenance supervisor I have under my purview 6.5 MW of diesel generators for which I am responsible for the maintenance. I actually do oil analysis on a regular basis for these units. The cost of oil analysis is in the neighborhood of $25 a pop , when you are looking at engines that have a 200L oil capacity each then it makes sense to spend a few bucks to determine the condition. I use Shell rotella 15-40 in my Benz and other vehicles. The cost of the oil is slightly more than the cost of the testing. So yes I will continue to change my oil at 3000 Mi intervals. I do believe in the science of oil analysis but the economy is just not that conclusive. Cheers Dan

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91 300D 603.960 (from japan) 194K
92 Toyota Diesel Landcruiser HDJ81-t 116K
02 Golf TDI new head courtesy of PO
87 300D
97 BMW 525 TDS Wagon 5spd
bunch of Onan and other diesel generators