Anything that cools engine fluids is beneficial. Oil coolers need to be tougher (higher pressures) and are more critical when it comes to rigging (requires special high pressure hoses and fittings). Then there's availability and cost. Heater cores are cheap and easy to find, operate on less pressure, and if you spring a leak, you're less likely to destroy your engine. For these reasons I prefer to improve the cooling system (more bang for your buck). Everybody has a different situation though, so cooling the oil might make more sense to some. Tim