Magnefine 3/8" Magnetic Inline Transmission Filter

The Magnefine is a sealed inline filter that installs directly in the 3/8 inch return cooler line between the transmission cooler and the transmission. It is the cheap insurance a lot of builders add after a rebuild or a converter swap: it traps the break-in debris and any leftover clutch and steel material that a pan filter alone will miss, keeping it out of the valve body and solenoids.

Inside it combines a pleated media element with a bypass valve and a magnet. The media catches non-ferrous material down to about 25 microns, the magnet pulls ferrous steel and clutch-plate particles down to roughly 3 microns, and the built-in bypass keeps flow moving if the element ever loads up in cold weather, so you do not starve the transmission of fluid. The 3/8 inch barbed ends fit the most common cooler-line size; check your line diameter and flow direction before you cut in.

Installation is straightforward: cut the return cooler line, slide the filter in with the arrow pointing in the direction of fluid flow back to the transmission, and clamp both ends. It is a favorite on high-mileage trucks, after a valve body or solenoid replacement, and on any unit where you want to protect the rebuild you just paid for. Replace it at your normal fluid service interval.