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  1. #1

    Default Emengency, Please help with coolant reservoir question

    I'm away from home on a short trip to the ocean. I was checking the fluid levels in the two reservoirs in the engine compartment on the driver's side, and noticed that they were both a little low. The outermost reservoir is obviously for radiator coolant, as I recognize the green antifreeze color. With the car cooled over night, the level is down about four inches from the top. Should I fill it up with antifreeze, or do I need that space for expansion once the car warms up?
    More importantly, the second reservoir, the one closer to the center of the car, is down about eight inches - just below the ring with all the holes in it. I'm a little embarrassed to ask, but what goes in this reservoir? Do I need to fill it back up, and if so, with what? I've got a 200 mile drive home, and am hesitant to do it without proper levels in these reservoirs.
    Thanks in advance for a speedy response! Rich or Dennis, are you out there? You did the 10 year maintenance about a year ago.
    Last edited by Roc Spo; 05-19-2017 at 11:43 AM.

  2. #2
    GT Owner KJRGT's Avatar
    Join Date
    May 2006


    There is supposed to be space in the tanks when cool.
    The inner tank is coolant for your engine, the outside tank is for your supercharger.
    Look on the inside of the tanks, toward the center of the car, and you will see two small windows, about the size of a quarter.
    That is proper level for both coolant tanks.

  3. #3
    GT Owner Sinovac's Avatar
    Join Date
    Jul 2006
    Largo, Florida


    The outer reservoir is for the supercharger and the inner is for engine coolant. Look at the level at thr site glasses on the bottles, not from the caps.

  4. #4
    GT Owner
    Join Date
    Apr 2012
    Oregon - state of twisties and few patrols.


    This is all explained in the manuals. However: the outer tank is the intercooler coolant fluid, the inner tank (that gets really hot!) is for the radiator/engine coolant. The level in the outer tank should be at the upper ring; the level in the inner tank should be at the lower ring. If fluid completely covers the inspection window in each tank, you're probably good to go. The levels will fluctuate somewhat with external temperature.

    But: it sounds as though your coolant (both tanks) is not the Ford specified one - that one is gold color, not green.

  5. #5
    gt owner & supporting vendor
    Join Date
    Feb 2006


    50/50 of Motorcraft Gold/Distilled water mix in each. The inboard tank is the Engine Coolant degas bottle - the outboard tank is the degas bottle for the intercooler. (Same mixture goes in each.) For piece of mind you can fill both - the correct level for the engine coolant (inboard tank) is to the lower edge of the bottom baffle. If you overfill it is no big deal as the car will puke out what it doesn't want.

    Use only the Motorcraft Gold and don't mix it with other formulas or you may significantly degrade its performance.
    Go to to see some "cool" GT products!

  6. #6


    Thank you all for your speedy responses - the GT Forum is the best!!
    I neglected to mention that I have a Hefner twin turbo conversion - maybe they specify a different fluid for the turbo intercooler.
    Upon closer inspection, the fluid in the inner tank appears to be gold, so I'm pretty sure it's right.
    Rich and Dennis do all of my maintenance work, and I can't imagine them using an incorrect fluid.
    Again, Thank You all.

  7. #7
    GT Owner FENZO's Avatar
    Join Date
    Jul 2008
    Lafayette, CO


    Not all GTs have sight glasses.

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