It does tell you whether or not it is worth while cranking her over.
You have to remember biodiesel is not as volatile as derv,and as such,you deffo need all 4 glow plugs available (on cold mornings anyway)-I would bet you find some dud when you check em.In our current weather,you should not need to add any petrol to bio-unless we head back to frosts.(petrol lowers the cetane value ,so only add when needed)
Mine has been on 100% for at least the last month.
Is there an easy way to test.glow plugs?
Thanks
Jon