Mobil 1 is advertising their 5-40 Synthetic for Truck application to go 80k between changes. However, they have 85qt cranks, massive filters, spinners and huge air filters and fuel water seperators. I concur with Larry on the other additive issues especially the detergents and viscosity enhancers which are so important in these applications. Unless your oil analysis includes assessment of additive comsumption I would be cautious. As to particulates; metal or non-ferrous should be caught by the filter, if indeed 1.0 micron is the spec. on Harvard filters. Redline sells inline heater that in theory removes excess water also. Hey, how anal can one get and what is the return on investment? I am with Larry's mantra, change hot and often.



Stephen