my 92 accor dcoupe seems to run cold. I had a new rad put in 9 month ago nd now the car doesn't seem to warm up.

this winter (chicago) I wouild drive to work and the gauge would never get above the first line above the "C". work is an hour away (40 mi) never used 5th gear.
pur cardboard over the rad and it would go about 1 third of the way into the "range" last night 50+degrees. I used 5th gear because I was low on gas and the car abgai never really warmed up. yes the heat was on (extra radiator, but I and I took the cardboard out, but I also advanced the timing last weekend. (I figured if I was runing cold a littel more timing woul be ok.

last summer (after the rad change) I could idle all day at the autocross at joliet and the gauge never got above 2/3 hot.(the trac surface tem was 120 ish) before the new rad the gauge would shoot up to hot hot hot. should I worry about this extra good cooling. am I loosing performance ie (how cold is too cold)

I think the gauge is good, I am not leaking. I suppose the thermostat coud be stuck open.