- Joined
- Feb 27, 2019
- Messages
- 631
What is better for preventing carbon build up? I know Shell 91 will give me better mileage because it is pure gas, but will ethanol burn cleaner?
This is for a 2019 WRX with the FA20 engine. Being purely DI I'd like to go with the option that will help slow the onset of carbon build up. I know it's inevitable regardless, just like in Audis, Mercs, BMWs, etc.
I care about performance not MPG. I'd rather go with 93 as I've read this engine on hot days can retard timing even on 91, so would rather have all the headroom I can get. But don't want to if the ethanol will hurt more than help.
This is for a 2019 WRX with the FA20 engine. Being purely DI I'd like to go with the option that will help slow the onset of carbon build up. I know it's inevitable regardless, just like in Audis, Mercs, BMWs, etc.
I care about performance not MPG. I'd rather go with 93 as I've read this engine on hot days can retard timing even on 91, so would rather have all the headroom I can get. But don't want to if the ethanol will hurt more than help.