The MGC uses a canister-type oil filter mounted vertically and prominently on the right-hand side of the engine block, a distinctive visual feature of the C-series engine bay, painted in the same silver-green as the engine itself and sometimes bearing a Tecalemit installation label. This is an entirely different system from the spin-on cartridge filter used on later MGB engines; no oil filter components are interchangeable between the two models. The canister housing is a permanent fixture on the engine, with the filter element replaced from within during servicing. The canister-type filter was standard BMC practice of the era and was shared in principle with the Austin-Healey 3000, though the MGC filter housing is specific to the C-series engine's oil gallery layout and mounting position.
Filter Elements
Two types of filter element are available: a paper element and a felt element, both fully interchangeable with one another within the same canister housing. The paper element provides effective filtration in normal road use, trapping particles down to a finer grade than the felt alternative. The felt element was the original factory specification and remains available for owners seeking period authenticity. The choice between the two is largely one of preference, both provide adequate filtration for the C-series engine in normal service.
The element should be replaced at every oil change, typically every 3,000 miles or annually, whichever comes sooner, as a clogged element restricts oil flow and can cause the bypass valve to open, allowing unfiltered oil to circulate through the engine bearings and cam followers.
Servicing the Oil Filter
Servicing the canister-type filter requires more steps than a modern spin-on change. The centre bolt at the top of the canister is unscrewed, allowing the canister body to be lowered and removed from the filter head, which remains attached to the engine block. This inevitably releases some oil, have a suitable drip tray positioned beneath the canister before removal. Once the canister is removed, the old element is lifted out and the inside of the canister cleaned thoroughly of sludge and deposits.
The new element is placed into the canister with the internal spring, pressure plates, felt washer, metal washer, and circlip reassembled in the correct order. The rubber sealing ring at the base of the canister and the centre bolt seal at the top should both be replaced at every element change, these are the primary sealing components, and reusing a hardened or deformed seal risks oil leakage that may not be immediately apparent but will cause a persistent oil drip and low oil pressure over time. Ensure the canister is fully seated against the filter head before tightening the centre bolt, cross-threading or over-tightening the centre bolt can damage the filter head casting.
Internal Components
Inside the canister, a spring sits between upper and lower pressure plates, with a felt washer and a metal plain washer between them. A circlip retains the assembly. A sealing washer at the filter head centre bolt completes the internal sealing. All of these internal components are available individually, when servicing the oil filter, it is good practice to replace the sealing ring and centre bolt seal at every element change, and to inspect the pressure plates, spring, and circlip at each service.
A weakened spring will not hold the pressure plates firmly against the element, allowing oil to bypass the element and circulate unfiltered, this is an invisible failure that causes accelerated bearing and camshaft wear without any visible external symptom.
Filter Head and Mounting
The oil filter head is mounted to the engine block with two bolts, spring washers, and plain washers, with a gasket between the head and the block face. Oil leakage at this joint, evidenced by oil weeping down the side of the block, indicates that the gasket or the bolt tightness needs attention. When renewing the filter head gasket, both mating surfaces should be cleaned thoroughly and the bolts tightened evenly to compress the gasket without distorting the housing. On cars fitted with an oil cooler, the oil cooler pipes connect at the filter head via unions with sealing washers, these unions and washers should be inspected for weeping at every oil filter service, as the filter head area is the most common source of oil leaks on the C-series engine.