for a mildly tuned 1660 crossflow, escort mk2 radiator with temp controlled electric fan.

which one to use and why? (for use on sunny south)

dontcha hate it when there is a choice, good job they donlt come in different colours!

I would suggest 88 if you have a heater, 82 otherwise.

Neither - get a 74 degree - QTH101K - no need to run an engine above that it as its just for emmissions - However if they are your proirity then go for 88.

There is no down side to 74C - better power - lower oil temps and still warm enough to prevent undue engine wear.

Andrew