Octane suggestions?
Thread Starter
Member
Joined: Oct 2014
Posts: 163
Likes: 4
From: Seattle, WA
2015 C300
Octane suggestions?
I know MB suggests at least 91, but what can I get away with in my 2015 C300? Some of the tech guys at my dealership said that it can actually be regular. I know there is an element of preference, but I wouldn't "hurt" the car if I put less than 91. . . .right?
MBWorld Fanatic!
Joined: Oct 2014
Posts: 4,524
Likes: 1,181
From: WI
17 E43; 21 GLS580
The question that always pops up. Yes you can use regular, no you shouldn't use it all the time. Although the engine can compensate for lower octane by retarding timing, when it does so, its operating at less than peak efficiency. This is specially bad for turbo engines since it makes it run hotter than it should. Personally I would only run regular gas only if premium is not available and on a single tank basis.
Last edited by c4004matic; Oct 24, 2014 at 08:05 PM.
Senior Member
Joined: Jan 2009
Posts: 281
Likes: 15
From: Los Angeles
2019 C43 AMG, 2017 Porsche Macan S, 2017 Mazda 3 HB
I agree with c4004matic. I talked to one of the guys who manages the loaners at a local Mercedes dealer and he said one of his C250's was so messed up from "cheap" people using regular gas that the engine was shot after around 15k miles. While I think this is an extreme case - I second the notion that turbo's run hotter than it should and regular gas cannot maintain/keep up with it.
Super Moderator
Joined: Jun 2008
Posts: 19,942
Likes: 192
From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
It depends which map the ECU is set to with a Star. But in general 91 AKI is the lowest octane fuel you should use or the timing will run perpetually retarded as the knock sensor detects the onset of knock. Not a good idea.
