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Older Corvettes are particularly susceptible to overheating problems in the lazy, hazy, crazy days of summer. But many Corvette owners, totally miffed by their car's susceptibility to overheating, have been heard to say things like, "I can't believe The General would let cars like this off the assembly line with such inadequate cooling" or, worse yet, "It's common knowledge that Corvettes have a tendency to run hot - that's why so many owners trailer their cars to shows." Oh, the myths and misinformation that runs so rampant through Corvettedom! The truth of the matter is that Corvettes were designed and engineered with quite a bit of attention to cooling their high-horsepower mills adequately even in very hot weather. But there are a few factors that have changed since these cars rolled off the assembly line. First, they were intended to run on high- octane leaded gasoline. In the heyday of my youth, you could get 103-octane Sunoco 260 right from the pump; not so today, not by a long shot. And, to compound the problem of lower octane, today's gasolines contain no lead. Why does unleaded, lower-octane fuel cause problems in these vintage Corvettes? Here's why: The higher the octane of a fuel, the slower and cooler it burns. A slow-burning high-octane gasoline results in more complete combustion which, in turn, delivers a lot more punch to the pistons. And, since lead (tetraethyl lead) in the gasoline acts as a lubricant, the engine also runs cooler since there is less friction in the combustion chamber and against the piston rings. Less friction means less heat. Lead also helps to boost the octane level of the gasoline.