In spite of new glow plugs, my 1985 300D will not start when the temp drops to around 20 degrees F overnight. Block heater is out of the question as I live off-grid. My buddy who drives a VW Rabbit says that VW recommends mixing up to 25% gasoline in the wintertime. I'm wondering if this will work on my Benz? I sure don't want to do it if it will damage the engine or fuel system. Anybody got any input on this? Thanks.....Dave