People seriously don't put mayo in the fridge...?
Call me old fashioned, but if it says 'keep refrigerated' on the bottle, that's exactly what I do. Because you know, I don't like eating semi mouldering foodstuffs and/or shitting through the eye of a needle.
I'm also really fussy about best before dates and keeping food generally; if in doubt, do without etc. (My bro's missus, who is otherwise lovely in all respects, is a food hoarder, forever sticking stuff back in the fridge, cupboards etc. for the nth time, saying 'I'm not wasting food, best before dates are a con to get you to buy more' etc, just as here. Her kids are forever spewing up with bugs etc, funny that
In terms of which sauce, Stokes every time - from old school glass bottle that doesn't taint the sauce. Actually tastes as though it's been made with (prime Italian) tomatoes. Glorious.
As for Mayo on chips, wrongness personified