[wrx.theo]

For a stock 2018 WRX with the fa-20 is there any benefits with running Petrocanada 94 over shells 91 v-power? Is my best option just using shells 91.

 

[zax]

What does the manual say?

 

[XJman]

You might see a little less timing adjustment but I believe the fa20 engines are capable of using sub premium fuel so using premium fuel would only give a little advantage.

 

[zax]

You might see a little less timing adjustment but I believe the fa20 engines are capable of using sub premium fuel so using premium fuel would only give a little advantage.

Capable, sure.

With the sensitivity to knock that these engines have, the ECU jumps at each and every opportunity to pull timing... even with 93 R+M/2 US gas from what I've seen. In that case, there would be definite advantages to running the most det-resistant fuel available.

But seriously... what does the manual say? Follow Subaru's guidelines. It may be regionally dependent.

 

[zax]

Does Canada use R+M/2 (AKI) or RON calculation?

 

[anarekist]

depending on the price diff i would use 94