How to Correctly Replace Antifreeze Fluid-25 in 5 Easy Steps

Changing your vehicle's coolant might sound like a job strictly for professional mechanics, but with the right preparation and a bit of patience, it is a manageable DIY task that can save you money. More importantly, doing it yourself ensures the job is done right, using high-quality products like Antifreeze Fluid-25.

This guide will walk you through the process of flushing and refilling your cooling system to ensure your engine is protected against extreme temperatures.
 

Before you pop the hood, you need to make sure you have everything ready. Running back to the auto parts store in the middle of a drain is frustrating.

What you will need:

• Antifreeze Fluid-25: Check your owner's manual for capacity, but usually, you will need 4–6 liters.
• Distilled Water: For flushing the system (tap water contains minerals that cause scale).
• Drain Pan: A large container to catch the old, toxic coolant.
• Funnel: Essential for pouring without spilling.
• Gloves & Safety Glasses: Coolant is toxic and can irritate the skin.
• Jack and Jack Stands: If your drain plug is located under the radiator shield.

⚠️ Critical Safety Warning: Never open the radiator cap or coolant reservoir when the engine is hot! The cooling system is pressurized, and boiling liquid can spray out, causing severe burns. Always wait for the engine to cool down completely (ideally, let it sit overnight).

Once the engine is cold, locate the coolant reservoir (a translucent plastic tank) and the radiator.

• Remove the Pressure Cap: Slowly twist the radiator cap or reservoir lid to release any residual pressure, then remove it completely.
• Locate the Drain Petcock: Look at the bottom of the radiator for a small valve (petcock). Place your drain pan underneath.
• Open the Valve: Unscrew the petcock or loosen the bottom hose clamp (if your car doesn't have a plug) to let the old fluid flow out.
• Dispose Properly: Old coolant is poisonous to pets and wildlife. Collect it in a sealed container and take it to a recycling center. Do not pour it down the drain.

Simply draining the old fluid leaves residue and old chemicals inside the engine block. To get the full benefit of Antifreeze Fluid-25, you need a clean slate.

• Close the Drain: Tighten the petcock or reattach the hose.
• Fill with Water: Pour distilled water into the radiator or reservoir until it reaches the "MAX" line.
• Run the Engine: Start the car and let it idle for about 10–15 minutes with the heater turned on high. This circulates the water through the entire system, including the heater core.
• Drain Again: Let the engine cool, then drain the water. If the water comes out very dirty, you may repeat this step until it runs clear.

Now comes the most important part. Antifreeze Fluid-25 is pre-mixed or concentrated (check the label), designed to protect your engine down to -25°C.

• Prepare the Mix: If using concentrated fluid, mix it with distilled water at a 50:50 ratio unless specified otherwise.
• Pour Slowly: Use your funnel to fill the radiator or reservoir with Antifreeze Fluid-25. Fill it up to the "MAX" or "FULL" line.
• Don't Overfill: Leave a little room for expansion.

Air pockets are the enemy of cooling systems. If air gets trapped, it can cause hot spots and overheating.

• Secure the Cap: Put the radiator or reservoir cap back on.
• Run the Engine: Start the car and let it idle. As the thermostat opens, the fluid level might drop.
• Top Up: If the level drops, carefully open the cap (use a rag to protect your hand) and add more Antifreeze Fluid-25 to bring it back to the correct level.
• Check for Leaks: Look under the car and around the hoses to ensure everything is tight.

Even with a simple guide, errors can happen. Here is how to avoid them:

• Mixing Colors: Never mix different types of coolant (e.g., mixing green silicate-based coolant with orange OAT coolant). This can cause the fluid to gel and clog your radiator. Stick to Antifreeze Fluid-25 for consistent chemistry.
• Using Tap Water: Tap water contains calcium and magnesium. Over time, these minerals build up scale inside your radiator, reducing its ability to cool the engine. Always use distilled water.
• Ignoring the Heater: If you don't run the heater during the fill process, air can get trapped in the heater core, meaning you will have no heat inside the cabin during winter.

Maintaining your cooling system is one of the most effective ways to extend the life of your vehicle. By following these 5 steps, you ensure that your engine is free of corrosive old fluid and protected by the superior thermal properties of Antifreeze Fluid-25.