I'm going to change the antifreeze out in my' 90 L-98 coupe. Any special tips I should know? And when replacing, how much is recommended for periodic freezing weather, and why only a 50/50 mix


Asked by Dec 26, 2014 at 01:52 PM about the 1990 Chevrolet Corvette Coupe

Question type: Maintenance & Repair

Recommended? Is a certain amount
of water needed in system? I'm
aware of using the GM type for the
aluminum parts. Can't find any help,
any input out there? Thanks
Gurus....... Kmac, again.

3 Answers


Unless you're having an overheating problem do NOT use any kind of chemical flushing agents (cleaner) in an older model such as yours. You'll be opening up a can of worms as something will spring a leak! Just use plain water. Once the drained water runs clear, usually after about 3 or 4 run "cycles" with the plain water, drain the radiator and refill with straight green or "all makes/all models type of antifreeze. On a 1990 model do NOT use Orange Dex-cool!! Then start the engine and let it fully warm up. Top off the radiator with straight antifreeze to the tip top of the filler neck. Then put the radiator cap on and fill the plastic recovery tank with a 50/50 mix of water/antifreeze to the " full hot " line. This procedure will give you a 50/50 mix in the cooling system. That's what you want. This will give you freeze protection to -30°F and boil over protection to 260°F. Never ever just run straight antifreeze! It is flammable!! Instances of it catching fire are rare but CAN happen!! HTH. -Jim

Best Answer

Hello again, i was looking around the radiator to find the petcock and noticed the front of radiator was packed full of debris, not leaves and paper, almost looked like mud and hair, maybe part of a roadkill. Have to take shroud, intake filter housing, etc, apart, to get in there to clean off. Hoping between that and fresh flush and new antifreeze, my overheating issue will scratched off the list. I'm hopefull. Anybody know where the petcock is?? Can't find it anywhere.


The petcock will be on the lower left (driver's side) of the radiator. Sounds like a critter climbed up in there to get warm and couldn't get back out. Thank you for the best answer click. HTH. -Jim

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