Are you looking for a continuous readout? If not take some black shoe polish and make a black circle on the
oil pan, near the bottom. Buy yourself a $35 infered gun set the emmisisvity to 1 (probably a default setting) and shoot the temp on the black spot.
Option 2 buy yourself a multimeter at sears that accepts the optional K type thermocouple and tape the thermocouple leads to the side of the
oil pan