So I replaced the coolant temp sensor recently, and it had a layer of orange stuff literally baked onto it. I looked into the coolant reservoir when replacing some of the coolant that leaked out when I was replacing the sensor and noticed that there was tons of orange-colored dirt, as if the coolant evaporated leaving this orange powder all over. I assume this is pretty bad and I should flush.

 

So is there a good flush procedure, or is it just drain, run some water through it from a garden hose, drain, distilled water, idle for 5 mins, drain, refill with antifreeze?

 

What about products like Peak radiator flush?

 

Which brand antifreeze should I use? The Subaru stuff is way too expensive, and I googled somewhere that Peak Global is essentially the same. What about Peak Long Life (not "Global")? It say that it's silicates and phosphates free, so would that work?

Drain the radiator, pull out the lower hose and t-stat, stick a garden hose in and flush.

I think all brands of antifreeze will work in a Subie. Just so many cars now with aluminum engine components that all mfgers. make antifreeze compatible with aluminum. I use Wallmart's house brand with no issues for years. Even says on the label that it is compatible with all engines.

 

20 to 30 years ago, there was a compatibility problem, but now solved.

 

Orange stuff in the cooling system is a mystery. Maybe PO put an additive in to address HG or leaking rad or heater core.

I've gone to Advance Auto's universal stuff for Suby's and most other cars.

 

Looks like Mountain Dew.

 

My local rediator shop uses it and recommends it.

 

I have obtained the Subaru real stuff for Skip (who isn't on here much at all - enjoying his retirement and travels) and it was really pricey for his wife's car. You know - the dark green stuff - looks like pond scum.

I think all brands of antifreeze will work in a Subie. Just so many cars now with aluminum engine components that all mfgers. make antifreeze compatible with aluminum. I use Wallmart's house brand with no issues for years. Even says on the label that it is compatible with all engines.

 

20 to 30 years ago, there was a compatibility problem, but now solved.

 

Orange stuff in the cooling system is a mystery. Maybe PO put an additive in to address HG or leaking rad or heater core.

 

Well, the coolant is orange, so it's almost like some of it evaporated leaving deposits, like what you'd get from boiling water. Same stuff was covering the sensor that I replaced. Is that typical to have that?

 

Otherwise, I can only think that the PO used tap water instead of distilled water, and I probably have limescale all over the engine.