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Old 08-27-2013, 11:42 PM
ExpensiveToys ExpensiveToys is offline
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On 2011 and newer Ram's anything with a lower temp setting than the stock thermostat is going to lower your gas mileage unless you live in a hot climate. Will even get worse in the winter if you have cold winters.

The performance profiles of the computer does everything possible to get the engine up to 190 degree zone to maximize fuel efficiency and lower emissions. If you put in a 180 stat it makes it more difficult for the engine to do that so it ends up running a different (warmup) performance profile and does things like not shutting off fuel to engine when coasting and/or keeping MDS from working. Basically its burning extra fuel trying to get engine up to temp. If ambient air temp or engine load isn't enough to get it up to 190 then it will keep burning extra fuel.

Its even worse of a problem on 2013/2014 as I they route engine coolant to a heat exchanger via an electronic thermostat to get transmission up to 190 temp to reduce wear and friction. In colder climates with a 180 thermostat it can start causing premature wear in the transmission.

There is a myth that the 180 thermostat in the 4th gen's helps with engine longevity but its actually bad for the engine and transmission, not to mention fuel economy. Go back to stock thermostat, its must better for your truck.
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