one gallon per thousand miles is trending towards high, one gallon per three thousand miles I would be happy with. Some people get twice that. It depends on many different parameters, but the 8V-71 is not a conservative engine from an oil consumption point of view. My engine is at the 2 to 3 thousand miles per gallon stage but it is quite new, only have about 4,000 miles on it at this point.Take a case of three gallons with you, check the oil level at the same bus level and temperature. The difference between hot and cold is about a half gallon in terms of simple expansion with temperature. Also, these engines often use far less oil slightly underfilled. I try to keep mine just over the fill mark on the dip stick.BrianA very good point, I learned long ago to never fill any engine to the full mark. I had an airplane that would throw out the first quart in ten minutes then go on for hours on the next quart. Same with both my DDs and just about every other vehicle I own.