Each engine is different and the maintenance of the engine changes the results. We run Chevron HDAX Low Ash in dozens of Waukesha engines, although most have sump capacities around 100 gallons. Consumption is reduced significantly over Group I oils, and We've got several that look excellent (2 to 3% oxidation or nitration with 4 0r 5 ppm of iron, etc.) after 3,000 hours. But we normally don't push them beyond that. But getting there requires the right fuel-air ration and the right operating temperatures.