Abstract: An engine oil filter is provided that comprises a transparent sidewall for inspecting the oil content within the oil filter interior. The oil filter comprises an oil filter housing with a filter element, a center tube, a base plate, and a biasing member that maintains the filter element in position within the filter housing. The filter housing has a sidewall that comprises a transparent material, thereby allowing inspection of the oil within the filter without having to first remove the filter from an engine. Also provided is an oil condition indicator that allows a user to compare the color of the oil within the oil filter housing to one or more oil reference markers. The oil condition indicator is used to determine when the oil has reached its usable life and when the oil must be replaced.