Planning cooling system maintenance

[Rooster2]

It has been three years now since I have changed coolant in my 99 OBW. I annually added a can of Prestone water pump lube and rust inhibitor to the system. Now, I think it is time for a flush and replace the antifreeze. I have also replaced the radiator cap. So far, so good, no issues with HG trouble on my EJ 2.5 phase 1.

 

I have no issues with existing thermostat, however, is it advisable to replace the thermostat? I bought this car used, so I have no idea how old the existing thermostat is.

[Legacy777]

I'd replace it. Make sure you use an OEM subaru thermostat.

[Rooster2]

I'd replace it. Make sure you use an OEM subaru thermostat.

 

Thanks, I was thinking of using an OEM thermostat. I have seen pixs here of OEM vs after market. OEM has the quality, after market looked poorly design and low quality.

[Legacy777]

Plus due to the difference in the shape the response to temperature is different and can cause a lot of weird things happening. I experienced this back in 96 or 97 when I first replaced the thermostat in my Legacy.

[eryque]

Is there a procedure to actually flush the coolant yourself, or do you just drain it and refill?

 

Also what do you do with the old antifreeze? Do parts stores take it back?

[Legacy777]

I normally will drain all the coolant out I can, fill with water, run the engine and heater to get the water in the heater core, and then drain the water out. Depending on what I get out, I may do that one more time before refilling with antifreeze/water mix.

 

Autoparts stores do sometimes take old oil & antifreeze. Some cities also have local recycling centers that take used oil & antifreeze.