Rapseed oil is fine to run your diesel engine on.
Rapseed oil won't freeze as fast as lets say olive oil. Try putting a liter
of rapseed oil in your refrigerator.
No problem running your diesel on rapseed oil. Drop it in your tank at a
mixture of 40% diesel and 60 rapseed oil is fine. More rapseed then ad 2
liters of kerosine to lower the viscosity (thinning).
Update on chainsaw oil:
My engine runs perfect on adding 4 liters of (cheep) chaisaw oil in 15/40W.
My engine 190 D 2.5 take 7 liters of oil in all. Runs very smooth. The
engine has run 670.000 km.