however, fuel consumption on these engines appears to go up in a non-linear fashion. This past winter we found ourselves sometimes running our 2GM20F for 8/10 hour days into the weather at 3000+ rpm our fuel consumption under these circumstances was slightly over 1/2 gal per hour - in comparison to just over 1/4 gal per hour at 2000 (an engine with high hours on it will not do this well). This can be a critical factor in an area where fueling stations are few and far between. Even when running only 2000+ rpm or so for long periods I always like to kick it up to 3K for the last 1/2 hour to "blow it out" so to speak. Seems to keep the combustion chambers and exhaust passages a lot cleaner over time. Diesels were designed to run near full out but it is not always necessary ...or desirable to do so.