Abstract: Apparatus and method for adding one or more additives to an engine lubricant, while the lubricant is circulating within an engine having an engine lubricant filter with a by-pass valve which opens when the pressure of the lubricant passing through the filter exceeds a pre-determined back-pressure value in which the apparatus further comprises an additive chamber containing one or more additives operably connected to the by-pass valve such that when the by-pass valve opens at the pre-determined back-pressure, at least some of the lubricant is caused to flow through the additive chamber and contact the one or more additives.

Abstract: A method for determining the condition of an engine lubricant passing through an engine and a filtration apparatus (1) with a filter by-pass valve (6) comprises determining whether the lubricant needs replacing according to whether a detector (9) detects that the extent to which the by-pass value (6) is at least partially open exceeds a pre-determined value.