the first time i ever saw any Plastiguage my brother was laying under a bus, with the oil pan off checking the clearances on a crankshaft to see how much ware he had, so he would know what size bearings to go back with. his choices was .001, .002, or .003. if it was worn more than that then he would have pulled the motor and had the shaft turned to .010. i call that checking for bearing size.