I understand how oil testing can help a company running a fleet of trucks. But I don't understand how a 1-shot analysis can help tell us anything about our engines or the suitability of an oil.

Trucking companies send in samples on a routine basis. They analyse for suspended contaminants, wear debris and perhaps remaining additives. Results assist in predicting required oil change frequency and maintenance needs.

By tracking results over the life of a particular engine, trends can be established which can help eliminate costly repairs. Don't imagine many individual car owners would do that.

BTW Barry - Here in Ontario, I used to use Mobil 15W50 before an engine overhaul on our 300D (when it was readily available). But now use Mobil 5w40 Turbo Truck & Diesel. Buy in USA because prices here are crazy high! Low pour point should help with winter starting.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5