I've finally got round to sticking the samples in the freezer. Not a scientific test at all as it's just one batch and not chilled in increments as I did for the HMPE water washing tests and there are no control samples.
BUT, the samples have been sitting for three days at -18°C and are still at least 50% liquid! I have to say that's the best cold weather fuel I've produced.

Sample on the right is straight bio, The one on the left has Cold Flow added.
They are thawing as I post ... I'll report any sediments (possible HMPEs) if they occur, but in my opinion the bio should be chilled slowly over a long period to be a fair test.