If it has never had any water/coolant added, then no it doesn't require antifreeze.
it could mean you need a new carburetor
Antifreeze does 2 things. First it protects your engine when the outside temperature is below freezing and the vehicle is not running. If the coolant freezes it could crack your engine block requiring a new engine. Caution: 100% antifreeze will also freeze up if it gets too cold. For best results you have to mix antifreeze and water. Check the antifreeze container for correct mixture. Antifreeze also has other things in it that keeps the water pump in good shape, prevents corrosion of the the radiator and helps transfer heat out of the engine. You need it even in hot weather.
If you find traces of oil in the antifreeze it's an indication of broken engine gasket. You need to go consult with a professional.
No the engine is not ruined. It needs a new head gasket and an oil change after the gasket been changed.
To change the antifreeze in your Ford 500, start by ensuring the engine is cool. Locate the radiator drain plug at the bottom of the radiator and open it to drain the old antifreeze into a container. Once drained, close the plug, then refill the radiator with a 50/50 mix of antifreeze and distilled water. Finally, run the engine with the heater on to circulate the new coolant, and check for leaks.
To change the antifreeze on a 2001 Polaris 325 Magnum, start by ensuring the engine is cool. Locate the radiator drain plug and open it to let the old antifreeze drain out completely. After draining, close the drain plug and fill the radiator with a mixture of fresh antifreeze and distilled water as per the manufacturer's specifications. Finally, run the engine for a few minutes to circulate the new antifreeze, then check for leaks and ensure the level is correct.
heater core is shot and you have to get a new one
You need a 50/50 mixture of water and antifreeze.
To replace the antifreeze in a 1985 Cadillac Seville, start by ensuring the engine is cool and then drain the old antifreeze by removing the drain plug on the radiator or using a siphon. Next, flush the cooling system with water to remove any residue, then close the drain plug. Refill the radiator with a 50/50 mixture of antifreeze and distilled water, ensuring to also fill the overflow reservoir. Finally, run the engine briefly to circulate the new antifreeze and check for leaks.
No worries, a few dollars from the wallet, perhaps, but not the thousands a new engine could cost. Do not drive the vehicle with that much antifreeze in the oil. Drain the oil, replace the oil and filter. Now drive around for a while (a day or two normal driving, assuming it's enough to get the engine up to normal operating temperatures). Replace the oil and filter again. This should be sufficient to cleanse the antifreeze from the system, but watch for white or antifreeze colored foam on the oil dipstick indicating the continued presence of water or antifreeze in the oil, in which case, replace the oil and filter again.
Make SURE the engine is COLD. Then unscrew the old sensor and install the new one. Antifreeze will leak out of the engine so be quit when replacing it.
An automotive product called "Bar's Leaks" will effectively seal any "small" coolant leak in the radiator but if the leak is coming from the engine area; this may require new freeze plugs and/or block sealer if the leak is not too serious.