I couldn't get mine started when it started to get cold, no mater how much i mixed it with diesel.
I'm not sure but i think it separates from diesel in your tank, so all you get through is pure oil cos it ran pretty crap when i first filled it up with a 50/50 mix. but when i got below half a tank it ran and started better.
But i have no glow plugs, just one of them silly cold start things.