Lower Thermost Temp

[Chuck61]

Hi Everyone,

I’m getting ready to perform my first coolant change on a 2015 Subaru Forester with about 130k. I bought a new thermostat to replace the original (which is still operating normally). I realized that the one I purchased on RockAuto opens at 188F, while the OE temp is 192. Will this make an appreciable difference? Am I going to cost myself money in fuel economy, or am I overthinking it? Thanks for any help.

 

[hrv]

Hi Everyone,

I’m getting ready to perform my first coolant change on a 2015 Subaru Forester with about 130k. I bought a new thermostat to replace the original (which is still operating normally). I realized that the one I purchased on RockAuto opens at 188F, while the OE temp is 192. Will this make an appreciable difference? Am I going to cost myself money in fuel economy, or am I overthinking it? Thanks for any help.

You are overthinking this... Just stick to what they came with... In the old days..60s...We would install a 160 thermostat to keep things cool...But engines now have many sensors and PCM that set all of the parameters of the engine to run right..

 

[Chris142]

You are overthinking this... Just stick to what they came with... In the old days..60s...We would install a 160 thermostat to keep things cool...

And increased bore wear and made sludge form.

 

[demarpaint]

I would only use an OE thermostat set to open at the temperature the engine originally called for.

 

[atikovi]

4 degrees wont matter. You won't even notice a difference on the temperature gauge. I'm sure the system goes into closed loop well before 188°F.

 

[hrv]

4 degrees wont matter. You won't even notice a difference on the temperature gauge. I'm sure the system goes into closed loop well before 188°F.

Stick to OEM temp...

 

[spasm3]

Hi Everyone,

I’m getting ready to perform my first coolant change on a 2015 Subaru Forester with about 130k. I bought a new thermostat to replace the original (which is still operating normally). I realized that the one I purchased on RockAuto opens at 188F, while the OE temp is 192. Will this make an appreciable difference? Am I going to cost myself money in fuel economy, or am I overthinking it? Thanks for any help.

In MA, I'd run the OE hotter thermostat.

 

[atikovi]

Stick to OEM temp...

Just the manufacturing tolerances of an oem stat could mean it too starts to open at 188.

 

[hrv]

Just the manufacturing tolerances of an oem stat could mean it too starts to open at 188.

maybe maybe not..

 

[SC Maintenance]

I wouldn't. The closed loop algorithm is tuned for the OEM spec. 4 degrees may not be much, but unless your the one that wrote the code you can't be sure.

Its not just about final temp but also about when it starts opening. Its a curve.

What exactly do you hope to gain from the new thermostat? If its running hot already, simply opening the stat sooner won't likely help much anyway

 

[spasm3]

Just the manufacturing tolerances of an oem stat could mean it too starts to open at 188.

Or it could be starting to open at 184. Who knows without testing.

 

[eljefino]

Thermostats have a luck of the draw, if you have a good one, stay with it. I'd put a scan tool on with it running normally to see what your "real" temperature is. Gauges are seriously deadened in the middle zone.

 

[atikovi]

Or it could be starting to open at 184. Who knows without testing.

I test every new thermostat before installing.

 

[spasm3]

I test every new thermostat before installing.

Same here.

 

[alcyon]

difference in 4 farenheit isnt gonna damage anything. The thing is the thermostat really opening at 188F. I bought a beck arenly that is supposed to open at 75 C but it opened at 70C...

 

[Marcozi]

The installation of aftermarket cooling system parts is strictly verboten!

 

[bullwinkle]

The installation of aftermarket cooling system parts is strictly verboten!

They do seem to be all over the place now. I could’ve cried when Stant got bought out by Motorad (who have consistently made junk IMO).

 

[GMBoy]

Sounds like an aftermarket part that fits several applications so they averaged the temp across all applications ended up with 188 as their spec to "mostly meet" each application they are selling it for.

 

[michaelluscher]

I'd wait for an OEM or OE part
If you have to go aftermarket, an Aisin thermostat would probably be best
You sure they didn't give you the thermostat for the opposite engine (NA vs Turbo?)

There's 3 different part numbers for a '15 Forester
Does the NA have dual thermostats?

Inspect your old ones carefully

 

[edyvw]

Who cares about 4 degrees Fahrenheit. The real issue is quality of thermostat. That is strictly OE part! Anything else is calling for a trouble.