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My 70 LT-1, since I purchased through a dealer I don't know what coolant is in the car currently. My toyota i use the toyota stuff and the green prestone in my 89 mustang. What would be a good coolant for the Corvette?
At the risk of getting too deep in the weeds, there are essentially two basic types of automotive coolant - the older types with Inorganic Acid Technology (IAT) and the newer types with Organic Acid Technology (OAT). You should always avoid mixing the two types because they each can degrade the other.
Back in the day, almost all engine blocks and heads were cast iron. Today, aluminum is the preferred choice for many manufacturers and the coolant industry has adjusted product accordingly. Many today offer a “universal” product but with anything that is a one-size-fits-all, there are compromises made.
You aren’t going to harm the car with any once choice of coolant. If you don’t know when the coolant was last changed, get it flushed by a reputable shop and enjoy your car.
I remember a set of BB Factory Aluminum Cylinder heads for sale at Corvettes@Carlisle that were original to an L88 or L89 made at the Winters Foundry with little snowflakes on the castings. I flipped them over and I saw the problem right away.
The heads had been eaten away by using the Old Green anti-freeze that was left in for too long. There was a huge hole in one of the castings and the only way to save the head would have required massive welding and machining. The heads were so damaged that not many people would have risked whet they were asking for them. It was sad to see how the damage had made the aluminum soft and it ate it away.
Green prestone. If running aluminium heads, intake and radiator, put an anode in the rad and a ground wire from rad to good clean ground, Done.
I have always used Zerex in all my muscle cars . Not a fan of the additive flush .. drain and rinse with water repeat until fairly clean . You won’t get it all but don’t worry about it as long as you change everything ; yrs or so depending on mileage you will be fine. Good luck