All parts really are not created equal, and the potential cost of using inferior parts is much greater than the savings you may achieve when buying the parts.

One big example of this is with aftermarket thermostats, we have yet to see one that even comes close to looking and functioning like the original Subaru part.  Now the effects of installing a lesser quality part may not be immediately known, there is no way that installing the below pictured component in lieu of the O.E. Subaru part is going to do your Subaru any bit of good.   The cooling system in a Subaru really has no margin for error and should always be in the best condition it can if you want to avoid costly repairs. 

The O.E Subaru is on the left, the aftermarket on the right there is really no comparison here.

A thermostat plays a much bigger role than it did in the past as vehicles now have both mechanical and electronic controls.  A weak part in the system can make it difficult for the vehicle’s computer to help regulate or maintain engine temperature based on its programming if the part that was originally installed has been taken out in favor of a thermostat that is not up to the task.  The thermostat starts to open as the cooling system temperature rises, then when the coolant in contact with the thermostat reaches the desired temperature it opens fully to allow full coolant flow.

This alone does not keep the vehicle’s cooling system from reaching the boiling point; the computer also plays a major role by monitoring coolant temperature with readings from the coolant temperature sensor and turning on the cooling fans when the temperature gets to the desired readings that are to be maintained.   A weak thermostat may affect the amount of time the cooling fans are on, and we have seen an aftermarket thermostat cause a “cooling fan rationality check” (PO483) code to be set by the vehicles computer and the check engine light to be illuminated as a result.  The computer is programmed to maintain the temperature for the best fuel economy possible and to help lower the vehicle’s emissions readings.

The cost to you for a thermostat could vary by only a couple of dollars in most cases, but the reason a general repair shop may revert to an aftermarket part is that the cost to them for an aftermarket thermostat will be much less than the O.E. Subaru part. The typical cost for an aftermarket thermostat is generally half the price of the Subaru part.  A good independent Subaru repair shop like All Wheel Drive Auto will know the right parts to use in your car, where we can save you some money, and where there is just no Substitute for the Original parts that came on your Subaru.

Thanks for reading

Justin