A plurality of heat receiving ribs are projected inwardly from the inner wall surfaces of a crankcase of a splashing oil lubrication type internal combustion engine. In various embodiments a density forest is trained using unlabeled data to estimate the data distribution. Additionally, a diaphanoscopic examination of the joint can be made with the same apparatus, and the results combined with the diameter information to identify or monitor a degree or progress of the inflamation. After the adjustment is made in this way, the thickness of the first insulating layer may be set to not greater than 90% of the thickness of the second insulating layer or may be omitted. In one embodiment, information pertaining to a specific transaction is communicated to a third party.