The present invention relates to a replaceable oil filter and method of using a replaceable oil filter that allows the oil filter to be disengaged from an engine without the spillage of residual used oil. Aligned forward and rearward slots are located in the ferrule generally parallel to the axis. A dissecting tool assembly is included. A storage unit stores reference identification information and a reference area range. The random number is preferably a multi-bit digital value, and each bit of the random number is determined in relation to whether the corresponding BEMF value is even or odd.