2004 Subaru WRX coolant flush

Hi all,

I have a 2004 Subaru WRX. While cleaning the car, I noticed that the coolant reservoir was almost empty! It has coolant to the “MIN” line, but that’s it.

I figure it’s almost time for a coolant change anyway (27.5k miles). I went and bought some Prestone coolant and flush, but when I got on the net, I read that there might be problems with gasket seals and leaks if you don’t use the OEM fluids.

It sounds like the Subaru Coolant Conditioner is necessary. However, my question is, can I used this conditioner with a generic antifreeze (like Prestone) or should I buy the OEM antifreeze? What could be in the OEM antifreeze that is so special?


My two Subarus have never used OEM antifreeze fluid, since the initial 30K service change out. Unless they have changed the owner’s manual (mine is 2003 model year), the requirement was for ethylene glycol antifreeze, which covers nearly every anti-freeze on the market. My mechanic uses the standard, generic “green”, because Subaru, regardless of the “Long-Life” statement on their antifreeze bottle, recommends changing it out every 30K miles (which to me is not long-life, but normal). Since this car averages 20K+ miles per year, I am changing out antifreeze every 18 months or so.

Watch the antifreeze consumption closely, since neither of my Subarus have ever used any antifreeze between changes. This consumption may indicate a potential a head gasket or other issue.

I do recommend the coolant conditioner, since my dealer sells it for less than $2, and that appears to be cheap insurance.

Buy the Subaru coolant conditioner for the $2 or so.

You can likely use prestone, Subaru WRX engines are not finicky about coolant. The only Subaru engine that is are the 2.5L non turbo motors.