An oil cooler reduces the temperature of the engine oil under sustained load, extending the oil's working life and protecting the engine from thermal-induced wear during hard use. The standard cooling system handles the coolant temperature well, but the engine oil, which carries away its share of combustion heat through the bearings and the piston cooling, sees temperatures that the original engine never quite addressed. Oil that consistently runs too hot loses viscosity and its ability to protect bearing surfaces, while thermal cycling accelerates the breakdown of the oil's additive package and shortens its useful service life, so for cars used hard, modified to higher outputs, or operating in sustained high-load conditions, an oil cooler is one of the most valuable engine-protection upgrades available, and on the three-bearing engines where bearing loads are concentrated across fewer journals than later five-bearing designs the benefit is particularly pronounced.
Kit Layouts & Cooler Sizes
The MGOC range covers two principal layouts and several cooler sizes. The Original Type kit follows the factory cooler arrangement with the cooler unions pointing downwards through holes in the radiator duct panel, supplied complete with rubber hoses and steel pipes with all fixings included, and the Accessory Type kit routes the hoses upwards through the radiator diaphragm panel with either rubber hoses or stainless braided hoses for owners wanting a more durable or visually distinctive installation. The cooler element itself is sized by the number of cooling rows, with 10-row and 13-row coolers produced to original specification matching the factory cooler size and suitable for road use on standard or mildly modified engines, 16-row coolers suiting cars used in warmer climates or with mild modifications, and 19-row being the largest stocked option intended for tuned engines or very hot climates, with all sizes using the same kit layout and only the cooler element changing. The factory cooler was an optional or standard fitment on some applications including the Twin Cam from launch and 1600 Mk II export cars, while many cars in the range were never factory-fitted with a cooler and benefit most from the retrofit, the addition being a straightforward modification using the appropriate kit and a bypass pipe stocked for cars where the cooler has been removed and the circuit needs to be closed.
The Cooler Matrix, Take-Off & Thermostats
The cooler matrix is a finned heat exchanger similar in construction to a small radiator that the engine oil flows through, with airflow over the fins carrying away the heat, mounted in the airstream at the front of the car typically in front of the radiator where the fast-flowing air gives the maximum cooling effect, with a larger element requiring more clear space behind the front apron. The oil lines connect the cooler to a take-off point on the engine, typically a sandwich plate fitted between the oil filter housing and the oil filter that has oil-flow paths routing the oil through the cooler before returning it to the engine. An oil cooler thermostat is fitted into the cooler circuit on most installations to prevent overcooling of the oil in cold weather, the thermostat blocking oil flow to the cooler until the oil reaches a set temperature, ensuring the engine warms up efficiently and the oil reaches its working viscosity as quickly as possible, particularly useful on cars driven through winter or in cooler climates where the cooler can otherwise reduce oil temperature below the optimal range. Without a thermostat the cooler operates continuously, which is acceptable for warm-climate or hard-use cars but lengthens the warm-up period.
Hoses, Service & Application
Stainless braided hose kits are stocked alongside rubber hose kits for the cooler-to-engine connections, the stainless braided option being more durable in long service and giving a cleaner engine-bay appearance, recommended for owners refurbishing an older installation as the original rubber hoses degrade with age and under-bonnet heat exposure. Individual hoses, mounting hardware, and fittings are stocked separately for routine servicing on cars with an existing installation, alongside the cooler elements themselves. Installation is workshop-level work but within the scope of a confident owner, the principal tasks being mounting the cooler at the front of the car, routing the oil lines cleanly with P-clips to prevent chafing, and fitting the take-off adapter in place of the standard oil filter mount, after which the system is filled with fresh oil, requiring slightly more than standard to account for the additional volume in the cooler and lines, and run to temperature with checks for leaks at the new joints. The investment pays back in extended oil life, reduced bearing wear, and the peace of mind of knowing the engine is running at a thermally-sustainable temperature under hard use.