I've just picked up my 2003 WRX from subaru dealer in Northumberland. He has told me that I can run the car on both 95 or 98 Ron fuel but not to swop between the 2 as it may cause problems. Todate the car has been run on 95 Ron, my intention is to run it on 97/98. Will I notice a difference and if yes how quickly will it occur?

Also does anyone know what problems may happen if different grades of fuel are used in the car?

Common question I know!

 

The ECU in Bugeyes and later models is supposed to automatically adjust fairly quickly if you swap between 95 and 97 or 98. So swapping should not be a problem.

It is said that an ordinary WRX can run on 95 all the time, but for maximum efficiency, it's better to stick to the likes of Optimax. STis are best run on 98 all the time, but 95 is possible and shouldn't cause any problem. If I had an Import or modded one - I would stick with the highest RON available.

I usually stick to Optimax for my Standard UK Spec. MY01 WRX but I have put in the odd tank of 95 Shell from time to time. In fact the Subaru dealer advised me to put one fill of 95 in for every three fills of 98.

Having said all this, my gut feeling is once you have decided a brand/RON, try to stick with it - there could be something in what your dealer has told you.

 

Forgot to mention, I'm sure that higher RON gives me marginally better MPG - so apart from car running smoother and better, some of the price premium is cancelled out.

 

Hi m8,shell optimax is what i run my 01 wrx on,that seems to be the best....if you can get it!,but super unleaded is what you want.

 

Shouldn't have a problem getting Optimax 99% of the time so will stick to the best!

 

Optimax is by far the best m8

 

You can swap between 95 and 97/8 RON as much as you like with the Newage WRX's no problems.