nowt wrong with 50/50 this time of year imo, I would only alter it when it gets really cold by adding up too and no more than 10% unleaded.
 
it is on a 300tdi so he won't be damaging the pump, just if we get a sudden cold snap it might take a bit of starting.
 
I run mine on a twin tank system so starts and finishes on diesel, but i've just started putting 5% unleaded in with the WVO
 

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