Heat cost

I believe so. The trick is, you don't want to get caught using home heating / farm oil on the highway. Years ago, even before factory diesel pickups became popular, some of the local loggers here were going around putting various diesels in mostly 1T Ferd 4x pickups. They started putting slip tanks in them to "fuel up" their log skidders and "accidently" plumbed 'em right into the pickup fuel systems. The enforcement guys got wise and laid a trap. It cost a few of em a bit of coin

Hey, it ain't that hard. All you have to do is crawl under there and look at the feed plumbing!!!