What You Need Before You Start
Changing radiator fluid in a 2016 Subaru Outback takes about 30 to 45 minutes and requires basic tools you likely already have. You will need a socket set, a drain pan, a funnel, fresh coolant (Subaru specifies a specific type — see below), distilled water, and jack stands if you need to access the drain plug from underneath. The job is straightforward enough that many owners do it themselves, though a shop will charge $150 to $300 for the same work.
Before you buy coolant, know that Subaru Outbacks use Subaru Super Coolant or an equivalent blue long-life coolant rated for Subaru vehicles. Do not use generic green coolant or coolant meant for other manufacturers — Subaru's cooling system is designed for their specific formula. A 2016 Outback holds approximately 5.5 quarts of coolant total, but you will typically drain and replace about 4 to 5 quarts depending on how much old fluid remains in the system.
Key Takeaways
- A 2016 Subaru Outback uses Subaru Super Coolant (blue), not generic green coolant, and you should never mix types.
- The radiator drain plug is located at the bottom of the radiator on the driver's side, and the engine must be completely cool before you open it.
- You will also need to drain the engine block drain plug (located on the passenger side of the engine block) to remove all old fluid.
- After refilling, you must bleed air from the system by running the engine and opening the bleeder valve on top of the engine until coolant flows without bubbles.
- The entire job takes 30 to 45 minutes and costs $30 to $60 in parts if you do it yourself.
Locate and Access the Drain Plugs
The radiator drain plug sits at the bottom of the radiator on the driver's side of the engine bay. It is a small plastic valve that you turn counterclockwise by hand or with a socket wrench — most owners can loosen it by hand once it is broken free. Before you touch it, make sure the engine is completely cold. If you have just driven the car, wait at least two hours. Coolant under pressure can cause serious burns.
The second drain point is the engine block drain plug, located on the passenger side of the engine block itself (not the radiator). This plug is slightly larger and also turns counterclockwise. You may need a socket wrench for this one. Draining both points ensures you remove as much old coolant as possible. Position your drain pan under each plug before opening it — old coolant will flow quickly once the plug breaks free.
Drain the Old Coolant
Open the radiator drain plug first and let the fluid drain completely into your pan. This usually takes 5 to 10 minutes. While it drains, open the radiator cap at the top of the radiator to speed the process and allow air to enter the system. Once the radiator stops dripping, move to the engine block drain plug and repeat. The engine block will drain more slowly and may yield another quart or so of old fluid.
Once both plugs have stopped dripping, close them hand-tight — do not over-tighten, as the plastic threads can strip easily. You now have old coolant in your pan. Check your local regulations for disposal; many auto parts stores and recycling centers accept old coolant for free, and some charge a small fee. Never pour coolant down a drain or into the ground.
Refill the System with Fresh Coolant
Pour fresh Subaru Super Coolant into the radiator using a funnel until the level reaches the "full" mark on the radiator itself. Do not overfill — the system needs room for expansion as the engine warms. Once the radiator is full, replace the radiator cap and move to the engine block drain plug area. Some owners pour a small amount of coolant directly into the engine block opening before closing the plug, though this is optional and depends on how much fluid drained from that point.
If your Outback has a separate coolant reservoir (a translucent plastic tank in the engine bay), fill that to the "full" line as well. This reservoir catches overflow as the engine heats and cools, so keeping it at the correct level prevents air from entering the main system.
Bleed Air from the Cooling System
Air pockets in the cooling system can cause overheating and poor heat output from the cabin. To remove air, locate the bleeder valve on top of the engine — it is a small screw or valve, usually near the thermostat housing on the passenger side of the engine. Start the engine and let it idle for 2 to 3 minutes until it reaches normal operating temperature. You should see the temperature gauge move into the normal range.
Once the engine is warm, carefully open the bleeder valve by turning it counterclockwise a quarter turn. You may hear a hiss as air escapes. Let it run until coolant flows steadily from the valve with no air bubbles, then close it hand-tight. Check the radiator level again and top off if needed. This bleeding step is critical — skipping it often leads to overheating complaints a few weeks later.
Check Your Work and Monitor the System
After you finish, let the engine idle for another 5 minutes, then turn it off and wait for it to cool completely. Once cool, check the radiator level one more time and the coolant reservoir level. Both should be at their full marks. Start the engine again and confirm that the temperature gauge stays in the normal range and does not climb toward the hot side.
Over the next week, check the coolant level once or twice. It is normal for the level to drop slightly as the system settles and any remaining air escapes, but it should stabilize. If the level continues to drop or if you see coolant pooling under the car, you may have a leak at one of the drain plugs or elsewhere in the system — tighten the drain plugs or have a shop inspect the radiator hoses and connections.
When to Change Radiator Fluid
Subaru recommends changing coolant every 105,000 miles or 5 years, whichever comes first. Some owners stretch this to 10 years if they use Subaru Super Coolant, which lasts longer than older green coolants. If your Outback is approaching either milestone, a fluid change is a good preventive step. Neglecting coolant changes can lead to corrosion inside the radiator and engine block, which eventually causes leaks and overheating.
If you notice the coolant color has turned brown or rusty instead of its original blue, that is a sign the fluid has degraded and should be changed regardless of mileage. Similarly, if the engine runs hot or the cabin heater blows cold air, a coolant flush may be needed to clear blockages.
Frequently Asked Questions
Can I mix old and new coolant?
No. Mixing old and new coolant can cause chemical reactions that reduce effectiveness and may clog the radiator. Always drain the system as completely as possible before adding fresh fluid. If you are topping off between full changes, use the same type and brand you originally filled with.
What if coolant leaks from the drain plugs after I close them?
The plastic threads on these plugs can strip if over-tightened or if the plug is old and worn. Tighten by hand until snug, then add a quarter turn with a wrench — no more. If it still leaks, the plug itself may need replacement. A new radiator drain plug costs $5 to $15 and takes 2 minutes to swap.
Do I need to flush the radiator before refilling?
A full flush with distilled water is optional for routine maintenance but recommended if the old coolant is brown or if the system has never been flushed. To flush, drain the old coolant, close the plugs, refill with distilled water only, run the engine for 10 minutes, then drain again. Repeat once more, then proceed with fresh coolant. This removes sediment and corrosion buildup.
Why does my temperature gauge climb after I change the coolant?
Air in the system prevents coolant from circulating properly, causing the engine to run hot. Go back and open the bleeder valve again to release trapped air. If the problem persists after bleeding, check that the radiator cap is sealing properly — a bad cap can allow air to enter during operation.
Is Subaru Super Coolant really necessary, or can I use another brand?
Subaru Super Coolant is formulated for Subaru's specific cooling system design and materials. Other blue long-life coolants rated for Subaru vehicles will work, but generic coolants or those meant for other manufacturers may cause corrosion or reduced heat transfer. Stick with Subaru-approved products to avoid problems.