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Engine Coolant Color Guide

Engine Cooling System

Mastering Engine Coolant Color

It’s fine to top up your coolant with a mixture of 1 part antifreeze to 1 part distilled water, (mixed together it becomes coolant) but it’s important to ensure that you use the same color coolant as is already in the car.

Water does two things that coolants shouldn’t do – it freezes and it boils. Both can cause damage to your engine. It’s important to use the coolant recommended by the vehicle manufacturer.

Coolant also contains addidtives which prevent eroding and corroding of your engine components.

The first place to look is in the owners manual, if a coolant color is specified, then go with that. If the color already in the car is different then you should flush it out, as some coolants contain additives that may not be suitable for your vehicle.

No – mixing different coolant colors can degrade and damage your cars cooling system. For example, putting an Orange or Red coolant in an older vehicle can eat away the yellow metals and solder in your cooling system.

Unfortuantely not – Coolant colors can be confusing because different types of coolant might have the same color. This happens because the water quality is different in different parts of the world. 

What color Engine Coolant should you use?

Engine coolant is one of the areas where it is important to stick to the vehicle manufacturers recommendations – you should consult your manual for the correct coolant for your vehicle, but as a guide:

Green and Yellow: Coolant for older engines. These colors are usually for older types of coolant that use inorganic acids to stop rust. They have a mix of silicates and phosphates, which is good for old cooling systems. These are IAT’s (Inorganic Acid Technology) and should not be mixed with Orange, Red, Pink or Blue Coolants.

We offer HOAT (Hybrid Organic Acid Technology) coolants, like G-05, which work well with many cooling systems. HOAT coolants usually don’t have phosphates but might have a little bit of silicates.

ZXG051

ZXG051 (zxg051) Zerex G-05 Coolant / Antifreeze - (Yellow G-05 Zerex) (1 Gallon)
$17.29

Orange and Red: Coolant for modern engines. These are for newer OAT coolants, often made with ethylene glycol and lasting about five years or 150,000 miles. A well-known type is Dex-Cool, used in SAAB and some GM engines. Remember, these orange and red coolants aren’t good for old cars. They can damage parts in older cooling systems and should never be mixed with Green or Yellow coolant.

Violet: Zerex G40 in violet is an OEM approved antifreeze/coolant mixture for BMW, Mercedes-Benz, Porsche and VW cars and light trucks, as well as older Audi and Volvo vehicles. It uses Si-Organic Acid Technology (SI-OAT) and includes a 5 year/150,000 mile guarantee against engine failure caused by freezing or boiling.

861399

861399 (861399) Zerex G-40 Coolant / Antifreeze - (Pink G40) (Prediluted) (1 Gallon)
$17.19

Purple, Blue, or Pink: Coolants in these colors are for specific engines as defined by the manufacturer. They could be HOAT, NOAT, or POAT types, which are special mixes. If you’re not sure your car needs one of these, be careful. It’s best to use them only if you know your car needs that specific type.

Can you rely on coolant colors?

Coolant colors can be tricky because different types of coolant might have the same color. This happens because the water quality is different in different parts of the world. For instance, in Europe, coolants don’t have phosphates because the water has a lot of minerals like calcium and magnesium, which don’t mix well with phosphates and can cause build-up. Most coolants from Asia don’t have silicates to keep seals safe. So, even if coolants from Europe, Japan, and Korea look the same color, they’re made differently.

The key thing to look out for is whether the coolant has silicates and phosphates. Most new cars use orange/red coolant that doesn’t have these. But some car makers still use them in their cooling systems.

There are also NOAT (Nitrite Organic Acid Technology), NMOAT (Nitrite Molybdate Organic Acid Technology), and POAT (Poly Organic Acid Technology) coolants, each made for different needs and to work well with different systems.

How to flush your cooling system

Flushing a car’s cooling system is an important maintenance task. Here’s a simplified guide on how to do it:

  1. Gather Your Supplies: You’ll need a coolant flush solution, fresh coolant, a drain pan, a funnel, and possibly a hose. A coolant flush solution is a cleaning products designed to remove dirt and rust from your cooling system.

  2. Cool Down: Ensure the engine is completely cool before you start. Never open the radiator cap on a hot engine.

  3. Drain the Coolant: Locate the radiator drain plug, usually found at the bottom of the radiator. Place your drain pan beneath it, and carefully open the plug to drain the old coolant into the pan. Some vehicles may require removing the lower radiator hose to drain the coolant.

  4. Flush the System: After draining the old coolant, close the drain plug or reattach the hose. Fill the radiator with the flush solution and distilled water as directed by the flush product instructions. Start the engine, turn the heater to maximum, and let it run until it reaches operating temperature. This circulates the flush solution to help remove buildup.

  5. Drain the Flush Solution: Turn off the engine, let it cool, then drain the flush solution as you did with the old coolant.

  6. Refill with Coolant: Close the drain plug or reattach the hose again. Fill the radiator with new coolant. Make sure to use the correct type of coolant for your vehicle. You might need to mix the coolant with water – check your vehicle’s specifications.

  7. Bleed the System: After filling, start the engine with the radiator cap off, allowing the coolant to circulate. This helps remove air pockets. Watch the coolant level and add more as needed. Replace the radiator cap once the engine reaches operating temperature and the coolant level stabilizes.

  8. Check for Leaks: After the process, check for any leaks under the vehicle.

  9. Dispose of Old Coolant Safely: Don’t pour old coolant down the drain or on the ground. Coolant is toxic and should be disposed of properly. Check with local waste disposal sites for guidelines.

Remember, always consult your vehicle’s manual for specific instructions related to your car.

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