I dare say this been covered many times before but what is the best route to take when cleaning rust from old tanks. Looking at some diy options, Viniger, electroylisis, lining products seem to be popular ? 

Over the years I have used probably most types of tank cleaning advice and the very best and cheapest was, string together with some wire a bunch of old nuts, the bigger the better, and pour in a 50-50 mix of white vinegar and water and rattle it round till its clean. Makes your arms ache and you look a right twit from behind  (I'm told by SWMBO!) then use heat to dry  it as quick as you can then use a sealer of your choice, just make sure it's ethanol proof.

Sorry should have added flush with distilled water once it's clean to counter the vinegar.

Are there any recommended liners .

i use POR15 from Frost, they do a motorcycle kit including the cleaner