So what do you do when gas is added to your tank unexpectantly

[ORCoaster]

Yeah but that requires forethought and preventative maintenance.  I think he just got unlucky with his fuel with the shear cold and ultra-temperature drop.  Not a normal occurrence. Maybe you need to run more of that anti-gel with colder temps?

And proof positive that you can use gas to thin diesel, just like the manual said you could.  At least on the older MK1 and 2. 

[srgtlord]

On the preventative maintenance side I have definitely done plenty on this old vw golf to push it from 200k to over 400k in the time I have owned it. I literally havnt had this problem in years since I started treating the diesel fuel. Im guessing there was an unusually large amount of water in the fuel from the last fillup......Oh well Ill just add waaaaay more antigel this time around and hope for the best....