So on my gas lid it says “ recommended minimum 91” does that mean I can just stay on 91 or should I use higher like 93 or 94?

 

I use shell nitro in all my cars. it was developed by shell and ferrari

https://www.shell.us/motorist/shell-...E&gclsrc=aw.ds

 

91 is minimum, but you may get slightly better performance (more like, less potential for knocking that can reduce performance, so not actually "better" performance) by using 93 or 94. The reason they say 91 is because some places don't offer anything above 91.

 

91 is what the US spec engines are tuned for. They make the full rated power at 91, because that's the lowest common denominator for premium across all states. However, you can fill with lower octane if you can't find at least 91, but AMG advises against doing WOT and putting lots of load on the engine, until you can fill it with 91 again. Also make sure you use Top Tier fuel brands as those have the necessary detergents to keep the fuel injectors from clogging.

https://www.toptiergas.com/gasoline-brands/

Filling up with 93 or higher doesn't really give you any more power unless you have an aftermarket tune that takes advantage of the higher octane. The factory tune doesn't as it can't advance the timing any further, it can only retard it in response to detecting knock. Aftermarket tunes take advantage of the higher octane level fuels available in some states to get more power out of the engine w/o additional upgrades, but on 91, these tunes only make minimal gains w/o drastically affecting the longevity of the engine. The factory 91 tunes pretty much already get most out of the engine, unless it's deliberately detuned as AMG does with the non-S models. In a non-S you can essentially get the same power as the S trim with an aftermarket tune and maybe a little above it, but significant gains can only be achieved with higher octane fuels.

Here in Cali, 91 is all we can get, and being at sea level, we essential get as much power as the engine can make with the stock tune. Turbo chargers can make up for elevation to a certain degree, but ultimately elevation is a bigger factor than octane, as long as the engine doesn't actually knock, and it shouldn't knock at 91. FWIW, I did European Delivery with my current AMG, and they retuned the engine for the higher octane fuel you can get in Europe while I was there. They don't use the same octane rating system over there, but the recommended minimum in Europe is 98 RON, which is roughly equivalent to 93 AKI here in North America. 91 AKI is roughly equivalent to 95 RON in Europe, which is midgrade. Once the car arrived in the US, the VPC retuned it for 91 AKI grade fuel and replaced the sticker inside of the fuel door.

 

Ethanol free 92 octane here in Texas