Are you SURE your engine is not getting appropriately warm?

Is your fuel gauge showing less fuel than you really have?

If this is the case look at the voltage regulator on the

back of your dash panel that controls both the temp and gas

gauge. May be you engine is OK but your temp gauge is not

showing it.

Otherwise you probably do have a thermostat not closing. It is

the thermostat that controls the actual temp at which the

cooling system operates. Any problem in the cooling system

will cause the ACTUAL (not indicated, necessarily) temp to go up.

Too much antifreeze will increase the freezing point from a minimum

of 68 below zero (F) for 2/3 antifreeze to 1/3 water to about

zero for 100% antifreeze.

If the weather is cold one problem is that frequently the thermostat

opens and closes rather suddenly so in very cold weather you have

a surge of very cold water in a warm engine, which is not good all

the way around but can especially be felt in your heater. That is

why the 444 and 544 as well as some of the earlier 122s had the

funky roller blind on a chain in front of the radiator. When it

gets cold again here I plan to put a piece of cardboard in front

of the radiators of both my 122 and my 164, to cover about 2/3 of the

radiator in each case. Keep it in till engine temps are no longer

controlled by the thermostat (and they start to rise a little higher

than normal) and then I'll take 'em out.

Normally a bad gauge voltage regulator will cause it to show hotter

than it is, however.