Kestas, the indirect injection mercedes are pretty rugged and can stand up to a lot of fuel abuse. Even in warm climates more than 20-25 percent filtered waste oil into the tank isnt reccomended without heating the fuel. I do know people that have been using 70%waste oil all summer in an unmodified car for several years with no problems though. The limiting factor is that it is hard on your injector pump. In cold enough weather the stuff could go solid in your fuel lines too. The main concern is your pump cuz that is big bucks if you screw it up. Mixing waste oil with about 10% gasolene to get the right viscosity is the cool new experimentation going on in the WVO message group lately. Check it out at http://biodiesel.infopop.cc/eve/ubb.x?a=frm&s=447609751&f=159605551

Eric Z
Chatt TN
79 300sd occasional straight into the tank wvo user.