GWM Tank 300 Coolant Guide: Spec, Capacity and What to Do If It Overheats
The GWM Tank 300 engine cooling system holds 7.9 litres of ethylene glycol based coolant. Regions outside alpine conditions use the No. 35 specification, while alpine regions use No. 45. Check the level in the overflow tank regularly and keep it between the minimum and maximum marks. If the engine overheats, park safely and shut it down, then never open the radiator cap while it is hot and never add coolant until the engine has completely cooled.
Coolant specification and capacity
| Attribute | Non-alpine regions | Alpine regions | Brake fluid | Washer fluid |
|---|---|---|---|---|
| Specification | Ethylene glycol based, No. 35 | Ethylene glycol based, No. 45 | DOT4 synthetic | Detergent, not soapy water |
| Measurement (capacity in litres) | 7.9 plus or minus 0.5 | 7.9 plus or minus 0.5 | 0.95 plus or minus 0.1 | 2.0 plus or minus 0.1 |
| Owner top-up | Yes, when cold | Yes, when cold | Level check only | Yes |
| Replacement | Authorised service centre | Authorised service centre | Authorised service centre | Owner |
These are design values. Actual quantities vary slightly with product, equipment and climate.
The reason for two grades is freezing point. Ethylene glycol is what lowers it, and colder regions need the higher specification to stay liquid when it matters.
Checking the level, safely
The check itself is simple. The safety around it is not optional.
- Work on a cold engine. Pressure remains in the system while it is hot.
- Look at the overflow tank, not the radiator, and open the lid slowly.
- Confirm the level sits between the minimum and maximum marks.
- If it is below minimum, top up with new coolant until it sits between the two marks.
- Clean any spill immediately, because coolant damages parts and paint.
Use only coolant that meets the specification. Mixing in whatever is on the shelf defeats both the freeze protection and the corrosion protection you paid for.
If the coolant needs replacing rather than topping up, that belongs at an authorised service centre.
Coolant is genuinely hazardous
Three rules that get ignored far too often.
- Do not let coolant contact skin or eyes. It contains harmful substances. Flush with plenty of clean water if it does.
- Seek medical advice immediately if it is swallowed.
- Do not tip it down a drain. Ethylene glycol causes water pollution.
The signs of overheating, in order
Extreme conditions bring this on: dragging, towing, climbing and overloading. Vehicle power drops away as it happens.
Watch for these together rather than in isolation:
- The water temperature indicator moves into the red zone
- The engine accelerates weakly
- Steam appears from the bonnet
- The air conditioning compressor stops working by itself
That last one surprises people. The vehicle is shedding load to protect the engine, not developing a second fault.
Our warning lights guide covers the high engine water temperature light, which is one of the symbols that means stop now rather than finish the trip.
What to do when it overheats
Follow this in order. Skipping a step is where injuries happen.
- Park safely and shut the engine down. Turn the air conditioning off if it is on.
- Check for steam from the bonnet. If there is none, open the bonnet and then start the engine. If there is steam, wait until it stops entirely, then open the bonnet and run the engine.
- Check whether the cooling fan is running. If it is not, shut the engine down and contact an authorised service centre. If it is running normally, wait for the water temperature to start dropping, then switch off.
- Check the coolant level and top up if it is low. Look for pipeline leakage at the same time, and call a service centre if you find any.
- Check the radiator core for foreign objects and remove anything lodged in it.
If the temperature gauge returns to the red range again while driving, head to the nearest authorised service centre rather than repeating the process.
The safety rules around a hot engine
- Do not open the bonnet while steam is coming from it. Serious burns are the likely result.
- Do not open the radiator cap or overflow tank lid while the radiator is hot. Escaping steam or coolant causes severe burns.
- When you do open a cap, cover it with cloth and open it slowly, and keep clear of the fan and belt.
- Never touch or approach the fan and belt with the engine running. Hands and clothing get caught.
- Do not add coolant to an overheated engine. Sudden addition can damage it. Wait until the engine has cooled completely.
That last rule is the one instinct argues against. The engine is hot, the coolant is low, and adding cold liquid feels like the fix. It is not.
Keep the radiator clean, especially after off-road use
Cooling problems often start with airflow rather than fluid. Check the radiator, fan and other heat-radiating components regularly, and clean anything particularly dirty.
After driving through water, sand or mud, check every time. Dirt packed into a radiator core reduces cooling capacity long before the gauge shows anything. Our towing and recovery guide covers the load conditions that push cooling systems hardest.
Questions owners actually ask
"Can I top up with water in an emergency?"
It will get you moving, but it dilutes both the freeze protection and the corrosion inhibitors. Treat it as a get-home measure and have the system corrected afterwards.
"Which grade do I need?"
No. 35 for regions outside alpine conditions and No. 45 for alpine regions. If you are unsure which category you live in, ask your service centre rather than guessing.
"The A/C cut out on a long climb. Is the compressor faulty?"
Not necessarily. The compressor can stop automatically as part of an overheating condition.