Is there a difference between the s4 and s5 thermostat? I ordered the set from mazda for my S5(Non-turbo), through mazda motor sports, and I recieved an s4 thermostat set (PN: 8AF1-15-171), needed the s5 version(PN: 8AF3-15-171). The s4 set has a paper gasket and the thermostat. The s5 has a rubber o-ring around the outside ring of the thermostat. So, is the thermostat the same and the difference is how it seals in the waterpump housing or is the thermostat different between the two series?

Thanks,
Rob

 

As the part numbers indicate they are different thermostats, I say that they cannot be interchanged. The S5 probably has a much thinner edge to fit in O ring groove.

 

I thought the part numbers might be different because the sets would include different seals... but I looked on mazdatrix and the 86-88 t-stats are different than the 89-92 t-stats. Is that because they "recommend"(sell) a stant t-stat for the s5's and the stock mazda t-stat for the s4's or are the thermostats really different between series?

 

Nevermind... They're different. Everywhere I've looked has them listed as different.