Abstract: The dipstick has an enlarged head and an integral, flexible shank which extends slidably through the dipstick tube of a conventional engine crankcase so that a pair of spaced thermistors, which are mounted on the shank adjacent its inner end, normally will be immersed beneath the level of the oil in the crankcase. The shank contains a ground conductor which is connected adjacent one end to one side of the thermistors, and adjacent its opposite end has sliding, resilient engagement with the inside of the dipstick tube. The opposite sides of the thermistors are connected by two additional conductors which extend upwardly in the shank to register with a pair of openings that are formed in diametrally sides of the shank near the dipstick head.