I have not heard of this before. Ford does however clearly state what percentage biodesiel you can use in the new 6.4 desiel engine. Guess the person should have read the owners manual or at least looked at the DVD you get with your 08 Super Duty. It is hard to blame the manufacturer for an engine failure when they clearly state what not to use for fuel. The same types of issues will probably surface when all the aftermarket items start to be put on these vehicles although Ford has clearly stated any aftermarket additions will void the warranty.