Choosing the right coolant for your Subaru isn't just a matter of convenience; it's about protecting your engine from potentially costly damage. The wrong coolant can lead to corrosion, overheating, and even engine failure. This guide will help you navigate the world of Subaru coolants, ensuring your engine stays happy and healthy.
Why Coolant Choice Matters So Much for Subarus
Subaru engines, particularly their horizontally opposed "boxer" engines, have unique cooling system designs. This makes them more sensitive to coolant type compared to engines with more conventional layouts. Here’s why getting it right is crucial:
- Corrosion Protection: Coolant contains additives that prevent corrosion of metal parts within the cooling system. Subaru engines often use different metals (aluminum block, iron sleeves, etc.), making them susceptible to galvanic corrosion if the wrong coolant is used.
- Freezing and Boiling Point Regulation: Coolant helps prevent the water in your cooling system from freezing in cold weather and boiling in hot weather. Using the wrong coolant, or the wrong coolant-to-water ratio, can lead to serious problems in extreme temperatures.
- Water Pump Lubrication: Coolant also lubricates the water pump, a critical component for circulating coolant throughout the engine. The correct coolant provides the proper lubrication to keep the water pump running smoothly.
- Head Gasket Protection: Subarus, particularly older models, have a reputation for head gasket issues. While not solely caused by coolant, using the incorrect type can exacerbate the problem by contributing to corrosion and overheating.
The Subaru Super Coolant: What Makes it Special?
Subaru specifies a particular type of coolant for its vehicles: Subaru Super Coolant. This is a long-life, ethylene glycol-based coolant that's formulated with specific corrosion inhibitors designed to protect the unique metals found in Subaru engines.
- Long Life: Subaru Super Coolant is designed to last for an extended period, typically up to 11 years or 137,500 miles on the initial fill. Subsequent replacements are usually recommended every 6 years or 75,000 miles.
- Blue Color: Subaru Super Coolant is typically blue in color, which helps distinguish it from other coolants. However, color alone isn't a reliable indicator of compatibility. Always check the label to confirm it meets Subaru's specifications.
- Phosphate-Free: Subaru Super Coolant is phosphate-free, which is important because phosphates can react with hard water minerals and form deposits that reduce cooling system efficiency.
Decoding the Coolant Jargon: OAT, HOAT, and IAT
You might encounter terms like OAT, HOAT, and IAT when researching coolants. These refer to different types of corrosion inhibitor technologies:
- OAT (Organic Acid Technology): OAT coolants use organic acids to protect against corrosion. They typically have a long service life.
- HOAT (Hybrid Organic Acid Technology): HOAT coolants combine organic acids with other inhibitors, such as silicates or phosphates. They offer a balance of long life and broad protection.
- IAT (Inorganic Acid Technology): IAT coolants use inorganic inhibitors like silicates and phosphates. They have a shorter service life than OAT or HOAT coolants.
Subaru Super Coolant is a HOAT coolant, but it has a specific formulation tailored for Subaru engines. Using a generic HOAT coolant might not provide the same level of protection.
Can I Use a Universal Coolant? The Risky Reality
Universal coolants are marketed as being compatible with all makes and models. While they might seem convenient, using a universal coolant in your Subaru is generally not recommended.
- Incompatible Additives: Universal coolants often contain a blend of additives that might not be compatible with the metals and seals in your Subaru's cooling system. This can lead to corrosion, leaks, and reduced cooling efficiency.
- Compromised Protection: To be "universal," these coolants often compromise on the specific protection required by certain engines, like Subaru's.
- Voided Warranty: Using a non-approved coolant could potentially void your Subaru's warranty if a cooling system-related problem arises.
Finding the Right Coolant: Part Numbers and Where to Buy
The best way to ensure you're using the correct coolant is to purchase Subaru Super Coolant from a reputable source. Here are some common part numbers:
- SOA868V9270: Subaru Super Coolant (1 Gallon Concentrate)
- SOA635071: Subaru Super Coolant (Pre-mixed 50/50)
You can purchase Subaru Super Coolant from:
- Your local Subaru dealership: This is the most reliable source for genuine Subaru coolant.
- Online retailers: Be sure to purchase from a reputable retailer to avoid counterfeit products.
- Some auto parts stores: Check the label carefully to ensure it meets Subaru's specifications.
Mixing Coolant: Concentrate vs. Pre-Mixed
Subaru Super Coolant is available in both concentrate and pre-mixed forms.
- Concentrate: Concentrate must be mixed with distilled water before use. The recommended ratio is typically 50/50 (50% coolant, 50% distilled water). In extremely cold climates, you can use a 60/40 mix (60% coolant, 40% distilled water), but never exceed 70% coolant.
- Pre-Mixed: Pre-mixed coolant is already diluted with distilled water and ready to use. This is the most convenient option, but it's also more expensive than concentrate.
Always use distilled water when mixing coolant. Tap water contains minerals that can react with the coolant additives and form deposits.
Step-by-Step: How to Check Your Coolant Level and Condition
Regularly checking your coolant level and condition is essential for maintaining your Subaru's cooling system.
- Park on a level surface and allow the engine to cool completely. Never open the coolant reservoir cap when the engine is hot, as the system is pressurized and hot coolant can spray out.
- Locate the coolant reservoir. This is usually a translucent plastic container near the radiator.
- Check the coolant level. The level should be between the "MIN" and "MAX" marks on the reservoir.
- Inspect the coolant's color and clarity. The coolant should be a clear blue color. If it's discolored, cloudy, or contains particles, it's time to flush and replace the coolant.
- Check for leaks. Inspect the hoses, radiator, and water pump for any signs of leaks.
Coolant Flush: When and How
A coolant flush involves draining the old coolant and replacing it with fresh coolant. This is typically recommended every 6 years or 75,000 miles after the initial fill.
- Why Flush? Over time, coolant loses its effectiveness due to the depletion of corrosion inhibitors. A flush removes old coolant, deposits, and contaminants, restoring the cooling system's efficiency.
- DIY vs. Professional: You can perform a coolant flush yourself if you're comfortable working on cars. However, it's important to follow the correct procedure and dispose of the old coolant properly. If you're not confident, it's best to have a professional mechanic perform the flush.
- Flushing Procedure (Simplified):
- Allow the engine to cool completely.
- Locate the radiator drain valve (usually at the bottom of the radiator).
- Open the drain valve and allow the old coolant to drain into a container.
- Close the drain valve.
- Fill the cooling system with distilled water.
- Run the engine for a few minutes.
- Allow the engine to cool completely.
- Drain the distilled water.
- Repeat steps 5-8 until the drained water is clear.
- Close the drain valve.
- Fill the cooling system with the correct mixture of Subaru Super Coolant and distilled water.
- Bleed the cooling system to remove any air pockets.
Important: Always consult your Subaru's owner's manual for specific instructions on coolant flushing.
Common Coolant Problems to Watch Out For
Here are some common coolant-related problems that can affect Subarus:
- Overheating: This can be caused by low coolant levels, a faulty thermostat, a clogged radiator, or a failing water pump.
- Coolant Leaks: Leaks can occur from hoses, the radiator, the water pump, or the head gaskets.
- Corrosion: Corrosion can damage the cooling system components and lead to leaks and overheating.
- Sludge Buildup: Sludge can clog the cooling system and reduce its efficiency.
- Head Gasket Failure: While not solely caused by coolant, using the wrong type or neglecting coolant maintenance can contribute to head gasket issues.
Frequently Asked Questions
- Can I mix different types of coolant? No, mixing different types of coolant is not recommended, as it can lead to chemical reactions and reduced cooling system efficiency. Always use the same type of coolant that's already in your vehicle.
- What happens if I use the wrong coolant? Using the wrong coolant can cause corrosion, leaks, overheating, and potentially engine damage. It's crucial to use the coolant specified by Subaru.
- How often should I check my coolant level? You should check your coolant level at least once a month, or more frequently if you notice any signs of leaks or overheating.
- Is it okay to add water to my coolant in an emergency? Adding water is okay in an emergency to prevent overheating, but you should have the system flushed and refilled with the correct coolant mixture as soon as possible.
- Where can I dispose of old coolant? Old coolant should be disposed of properly at a recycling center or auto parts store. Never pour coolant down the drain or onto the ground.
The Bottom Line
Using the correct coolant, specifically Subaru Super Coolant, is vital for maintaining the health and longevity of your Subaru's engine. Avoid using universal coolants and stick to the recommended maintenance schedule to prevent costly repairs down the road. Regular checks and timely coolant flushes are your best defense against cooling system problems.