Spin-on Oil Filters with Anti-Drain or Anti-Return back Valves

Most spin-on oil filters have an anti-drain back valve. The function of this valve is to retain a sufficient amount of oil within the filter housing itself, ensuring that oil reaches the cylinders and other components requiring lubrication immediately upon engine startup. If the flow of oil to the engine is interrupted-even briefly- when the engine runs without oil and cause wear of moving parts due to initial lack of oil, serious damage will occur due to component friction and affecting cylinders, pistons, & etc.

As we said, most spin-on oil filters feature one anti-drain/return valve in the form of a flexible membrane made of materials such as Silicone, Nitrile (NBR) or similar compounds on the dirty side/entrance.

Advantages of Using Double Anti-Drain Valve

As shown in the figure below, the filter contains two valves; one on the clean oil side and the other on the dirty (unfiltered) oil side. Clean oil flows through one, while dirty oil flows through the other.

Incorporating these two valves not only ensures the filter housing remains fully filled with oil, but also minimizes oil spillage onto the engine block during replacement. In other words;

1. The engine never runs without oil,
2. oil loss is minimized during filter replacement

figure of single and double valve filter