While we are on the discussion of = diesel lube oils, I strongly reccommend Chevron Delo 400 15-40 for most all diesel applications (except Detroit Diesel 2 stroke engines, then you use Delo = 100 series). This is the oil our whole fishing fleet back at home uses = this oil, and we have no problems with it. There are many engines that = use this stuff and go 20,000 hours (and more) between rebuilds running this = stuff, and these engines range in size from little .9 L single cyl. engines to = 1200+HP 38L V-12's. My dad has run this stuff in his '84 GL since we got it in = '85 w/ 5k miles on it. That engine lasted 155k miles before we replaced = it due to bad compression (it still ran strong, just blew oil out the rear crank = seal if we were climbing a long grade and lugging the engine).....Another plus = is that you can buy this stuff by the quart, gallon, or barell, and it is not = all that expensive. I have a question, have any of you guys out there had = oil samples taken and submitted them to an analysis lab? This is = another common practice in our fleet, and it actually can detect an engine = failure coming up because the lab can detect small amounts of fuel, metal, and = coolant (head gaskets....) in the oil, before we could even see a change in any = thing, sorta like a peek into the future....