There are temp probe units that will plug into an existing digital volt ohm meter that will allow you to read temperature in fahrenheit degrees as millivolts. You will have to go to an electronics outlet that handles Wavetek or Fluke instruments (or many others I would think). The unit will have a wire probe that you can slip past a loosened upper radiator hose and then tighten the hose clamp and drive. It can also be slid down trans or oil dipstick tubes for temporary oil temp readings (carefully determining when it will just touch oil so as to not be wound around crankshaft or internal rotating parts of trans).