Washing things at 60 degrees - does this set stains?

[Pennies]

I read somewhere once that washing stuff at anything above 40 degrees will set a stain. We've just got back from hols and a 40 degree wash simply hasn't done anything to get rid of the hot chocolate / painting / suncream stains (I know the latter are unlikely ever to shift though).

If I stick a load of Vanish on them and bung them in at 60 will the stains set?

Just wash everything a lot hotter with twice the Ariel.

I got horrid set in grass/mud stains out of my stepsons' jeans by washing them at 90° with two liquitabs. Jeans are fine, like new.

Chocolate is a bummer though it washes out after several washes IME.