Caddies are known to have the best climate control systems in the business, and as far as the heating system goes, that's attributable to the fat, high-flow Cadillac heater core nestled in the dash of your Eldorado or CTS. Back in the days of 500 cubic inch engines, it wasn't hard to find some heat with which to power a Cadillac heater core either. You see, a Cadillac heater core operates by circulating the hot engine coolant through a network of tubes and passages, just like a small engine radiator. And since a gasoline engine is only about 15-25% efficient, 500 cubic inches provides a good bit of heat for the Cadillac heater core to work with! As for keeping your Cadillac heater core in good condition, the best thing you can do is to change your coolant every other year, refilling the system with a 50/50 mix of antifreeze and water (or the ratio specified in your owner's manual). The corrosion inhibitors in fresh antifreeze keep the Cadillac heater core from rusting internally, which is where Cadillac heater core problems tend to begin. Either the corrosion itself causes a leak in the Cadillac heater core, or the rust particles break off and clog the small tubes in the Cadillac heater core. A leak is the worst case scenario, since coolant running from your Cadillac heater core ends up in the interior of your vehicle where it can do significant damage. However, a clogged Cadillac heater core often leads to a leak because pressure builds up as a result of reduced circulation. The pressure then creates a leak by bursting one of the soldered seams in the Cadillac heater core. Since a Cadillac heater core tends to be a bear to replace, you'll save yourself money and trouble by maintaining your heating and cooling system. Plus you'll have the advantage of a fully-functional Cadillac heater core to keep you warm on those snowy February mornings.