Mazda 1978 GLC Instructions; Maintenance And Servicing page 53

You should keep the freeze protection at an adequate
level for the temperatures which may occur in the
area where your vehicle will be operated.
Note:
Water with an anti-rust inhibitor for aluminium engine
parts in areas where the temperature is always above
freezing. Replace the water and rust inhibitor every
6 months.
CHANGING COOLANT
Every 25,000 miles or two years whichever comes first.
the coolant should be changed.
1. Remove the radiator cap when the engine is cool.
2. Move the heater temperature control lever to the
" HOT" position.
3. Open the drain plugs. let the coolant drain out.
then reinstall the plugs.
4. Flush the cooling system out with water, drain and
reinstall the plugs.
5. Add a mixture of ethylene glycol anti-freeze for
aluminum-engine parts and water to provide required
freezing and corrosion protection. For purpose of
mixture, refer to the following table.
6. Run the engine at idle until it reaches normal
operating temperature. Install the radiator cap.
7-9
) ~
~J
Engine drain plug
Protection
Above
3 0F (-16°C)
Above
_15°F (-26°C)
Above
- 400F
(--40
0 C)
Radiator drain plug
Mixture percentage
(v olume)
An,i·freeze so lu tion
Water
35 6 5
45 55
55 45
7. Inspect all connections for leaks. Check the coolant
level and add more coolant if required.
Caution:
1. Do
n01
use alcohol or methanol base coolants.
2. Use only soft (demineralized) water in the coolant
mixture.