Reische Performance Thermostat 170 Degree Performance Cobra 1996-2004/Mach 1 2003-2004/GT 2005-2006

Reische Performance:
99% of 100


  • 170 Degree Thermostat
  • Direct-Fit
  • Easy Installation
  • OEM Style

Reische Performance 170 Degree Performance Thermostat for all 1996, 1997, 1998, 1999, 2000, 2001, 2003 and 2004 Cobra Mustangs, 2003-2004 Mach 1 Mustangs and 2005-2006 GT Mustangs.

Keep your 1996-2004 Cobra, 2003-2004 Mach 1 or 2005-2006 GT Mustang's engine at an optimum running temperature with help from Reische Performance and their 170 degree performance thermostat! These Reische 170 degree, direct-fit thermostats are custom made with the same size diaphragm and bypass control as the OEM thermostats; proper bypass control means maximum efficiency from your cooling system. Every thermostat from Riesche Performance is modified by hand using only American made parts and then quality inspected to ensure consistent opening temperatures.

- 1996-2004 4.6L 32V DOHC Cobra Mustangs
- 2003-2004 4.6L 32V DOHC Mach 1 Mustangs
- 2005-2006 4.6L 3V SOHC GT Mustangs

Additional Fitments:
- 2003-2004 4.6L 32V DOHC Mercury Marauder

Whether you are using an aftermarket radiator or not, this performance thermostat will provide the best possible heat dissipation from your setup along with a faster warm up time and better cold weather performance than a 160 degree unit or a thermostat with holes drilled in the diaphragm. Reische believes the 170 degree opening temperature is the ideal balance for high performance engines, providing high flow to your radiator by mid-180 temperatures while still providing good all season performance. With proper fan settings your coolant temperatures in cool weather will be in the 170s and in hot weather the 180s, giving those running high levels of timing and/or boost added protection against engine-damaging detonation as well as maximum power output.

This Reische Performance thermostat ships with a new o-ring, coolant ratio/additive recommendations and specific fan settings for popular handheld tuners.

Will I benefit from a low temperature thermostat?

A lot of people ask this question and the short answer is, probably. Typically, Reische does not recommend one if your engine is still running on the stock tuning; simply because a cooler engine does not necessarily make more horsepower. Sure, you may lose a few degrees of incoming air temperature and see some small gains, but primarily you should 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. 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 degrees can run more timing advance safely than one running at 205 degrees, so tuning, along with a low temp thermostat, can make some significant gains. If you're using a handheld programmer, chip or custom tune then yes, it is definitely recommended to use a Reische Performance 170 degree thermostat. 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.

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

If the engine does not reach a high enough temperature for the computer to leave warm-up mode then fuel economy will drop dramatically. This is the reason Reische does not produce or recommend for street use: 160 degree thermostats, running no thermostat at all or drilling holes in a thermostat. However, in all the time Reische has been producing their 170 degree performance thermostats, there has not been one complaint of anyone losing fuel economy. Reische thoroughly believes 170 degrees is the best balance overall.

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 a Reische 170 degree thermostat in cold weather, but to be safe, Reische recommends 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 it is recommended to use a quality 0W-30 (or 5W-30) synthetic oil for most late model applications. In extreme cold environments it may be best to run an OEM temperature thermostat, but above all just monitor your coolant temperature carefully when you have concerns. If you observe sustained engine coolant temps below 165 degrees then it is recommended to swap the OEM thermostat back in for the colder months.

Please Note: It is important that the fan settings in your tune are set up properly to see the best possible heat dissipation from your cooling system. Otherwise a low temperature thermostat will only be effective when the vehicle is moving because heat cannot be removed unless there is air flowing through the radiator. Typically with a Reische 170 degree thermostat installed, your cooling fan(s) should be set to turn on between 184-190 degrees and shut off between 176-182 degrees, if not then re-flash your tune with the appropriate settings.

Tech Tips: Thermostats tend to have faulty operation or stick after years of service. Replace the thermostat during regular tune-ups to keep everything working properly. Adding new coolant with the thermostat will help keep your engine running at its proper operating temperature.

Beware of aftermarket companies who sell the same universal thermostat for all Ford engines. Reische Performance thermostats are the only ones designed to precisely fit each application, making them the best performing low temperature thermostats on the market. Order your 1996-2004 Cobra Mustang, 2003-2004 Mach 1 Mustang and 2005-2006 GT Mustang Reische Performance 170 Degree Performance Thermostat from CJ Pony Parts today!

California Residents: Proposition 65 Warning

Vehicle Fitment

This product will fit the following Mustang years:

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