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Will I benefit from a low temperature thermostat?

A lot of people ask me this question and the short answer is... probably. But typically I don't recommend one if your engine is still running on the stock tuning. Simply because a cooler engine does not necessarily make much more horsepower. Sure you may lose a few degrees of incoming air temperature and see some small gains but primarily I like to think of lower coolant temperatures as protection against engine-damaging detonation. Remember the knocking sound you heard when trying to accelerate an overheating vehicle? That is detonation and this can quickly destroy a high horsepower engine being pushed to maximum performance. But aside from possibly saving your engine there are a couple ways that a low temp thermostat can actually help make more power:

An engine at 185° can run more timing advance safely than one running at 205° so tuning, along with a low temp thermostat, can make some significant gains. So if you're using a handheld programmer, chip or custom tune then yes, I definitely recommend one of our 170° thermostats. Running an engine cooler has been an A-B-C of high performance since the early days of hot rodding, ask your dad or grandfather. Those guys were pulling their thermostats out or drilling holes in them because they knew they could run more timing by doing so.

I remember one time racing another identical vehicle with similar modifications 3 times consecutively. The first run was very close with me barely edging him out. The second run I pulled away noticeably harder and by the 3rd run I was just walking away... Why? Cooling mods... his thermostat and intercooler heat exchanger were stock. Keep the heat out and maintain more consistent horsepower.

What are the possible negative effects of a low temperature thermostat?

If the engine does not reach a high enough temp for the computer to leave warm-up mode then fuel economy will drop dramatically. This is the reason we do not produce or recommend for street use: 160° thermostats, running no thermostat or drilling holes in a thermostat. However in all the time we've been producing our 170° Performance Thermostats there is rarely ever a complaint of anyone losing fuel economy. I really believe 170° is the best balance overall and apparently Subaru agrees as 170° is OEM temp for many of their late model engines. Our competitors may recommend their 160° thermostats but I just don't think they make sense for most street applications, primarily because most vehicle's OEM cooling systems do not dissipate heat effectively enough to make a difference under hotter, more demanding conditions. An engine running a 160° thermostat will always run cooler than ideal in colder ambient temps but will see little to no benefit at all when it matters most.

Another concern is oil temperature and viscosity. If the engine oil does not get hot enough to burn off certain contaminants then the oil's effective life will be reduced. Lab testing has not shown any significant contaminant increases using our 170° thermostats in cold weather, but to be safe, I recommend changing your oil more frequently if you plan to operate your vehicle regularly in cold climates. Also, effective oil viscosity is increased with lower temperatures so I would recommend using a quality 0W-30 (or 5W-30) synthetic oil for most late model applications. Even though Ford recommends 5W-50 oil for many of their late model high performance applications I would still recommend the 30W oils stated above when it is being operated regularly in cold weather with our 170° thermostat installed. In extreme cold environments it may be best to run an OEM temp thermostat but above all just monitor your coolant temperature carefully when you have concerns. If you observe sustained engine coolant temps below 165° then I recommend swapping in the OEM thermostat for the colder months.

Some engines may exhibit a slight decrease in fuel economy with lower coolant temps but typically not more than 1 MPG. I believe this is the trade off made for the improved throttle response of a more effective powerplant or could just be an indication that some minor adjustments need to be made in the tune.

As always, if you have any questions or concerns about our products feel free to Contact Us and please be safe out there.

-Joel Miller - Owner & Operations Manager

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