So, my old man's excentric. Fine. He's got a new duramax powered pick em up truck, a mechanic shop, and a lot of crazy ideas. He says he's putting 5 gallons of used ATF with a 32 gallon tankfull of diesel. In other words he's using 5 gallons of atf in place of 5 gallons of diesel which means he saves about 15 bucks a tank full. He says he filters the atf through a 10 micron filter bag first. Is this insane or normal?