The original MGB oil filter is a cannister type that requires the metal housing to be disassembled to replace the internal paper element, a process that inevitably produces spilled oil, disturbs the sealing rings, and takes considerably longer than a modern spin-on filter change. For owners who want the convenience of a quick and clean oil filter service, a spin-on conversion kit provides a simple and effective upgrade. The conversion replaces the original cannister arrangement with an adaptor that accepts a standard disposable spin-on filter of the type used on virtually all modern cars. Installation is straightforward, the conversion bolts directly to the existing filter housing in place of the original cannister, and the changeover can be completed with basic tools.
Beyond convenience, the spin-on conversion offers a practical advantage on cars where the original filter was an upright-mounted type. A spin-on cannister fitted in the upright position can incorporate a non-return valve that prevents oil from draining out of the filter when the engine is not running. On an engine without this feature, the filter empties between uses and the engine runs momentarily without filtered oil pressure on each start-up, a brief but repeated period of under-lubrication that contributes to long-term bearing and camshaft wear.
For cars that are driven infrequently or stored between outings, this benefit is particularly worthwhile. The conversion is fully reversible. The spin-on adaptor can be unbolted and the original cannister refitted at any time, useful for owners who wish to present the car in original specification for concours judging while using the conversion for everyday driving. Disposable spin-on filter cannisters are available for ongoing replacement, and should be changed at every oil service interval along with the engine oil.