89 or 91 gas?
MBWorld Fanatic!
Joined: Apr 2003
Posts: 1,252
Likes: 2
From: San Antonio, Texas
2016 BMW Z4 sDrive35i M Sport
This topic has been beaten to death, but you should always use the factory reccommended gasoline grade. Some people have run 87 with no problem, me personally, I ran 87 once and my car stalled and ran like ****.
Out Of Control!!
Joined: Apr 2002
Posts: 20,081
Likes: 0
From: Chicago
Volvo V90 CC
There's a reason they say Premium recommended, if you own a Benz you should pay the price, get a chevy or a honda and you'll be perfectly fine using 87 or 89. besides if you really think about it and do the math you'll only be saving about $ 2.70 (at the most) per 18 gallon fill up at the risk of long term injury to your engine, knocking, less mpg, etc (all of this is just the risk).......my 2 cents 
Super Member
Joined: May 2004
Posts: 579
Likes: 0
From: ...
...
I was just about to make a thread kinda like this...Iwas at the gas station filling up & told the guy (who was talking on his mobile phone) fill it up premium. When I hear the hose click turn around to find out he put in plus (mid-grade~89) I got the guys name spoke to the manager & told him he put in the wrong thing & if any thing happens that they are responsible..they both had a look on their faces like "yeah righ".
I was at a little more than 1/4 of a tank, havent noticed any problems except there seems to be a strange smell in the inside...i didnt notice until 2 days later, dont know if its related
I was at a little more than 1/4 of a tank, havent noticed any problems except there seems to be a strange smell in the inside...i didnt notice until 2 days later, dont know if its related
Out Of Control!!
Joined: Oct 2004
Posts: 20,773
Likes: 0
From: Maryland, USA
2007 CLK350 Sport, 2006 E320 CDI, 1978 Cessna 152
There was a Car And Driver article a year or so ago that detailed whether using a different grade of fuel really matter. They tested a mustang, a M3 and maybe a couple other cars (this is based on my memory recall so dont quote me on it). They found that for cars that are made for premium using a lesser grade only hurts performance a little bit but had no comment whether it hurt the engine or anything else. They also said that if you run a car made for just regular unleaded on premium little if any power gain results.
There was also a CarTalk episode dealing with the same issues and they stated that the altitude of where you live has an impact on rating of the fuel. For example, if you live in Denver (elevation 5'280 ft give or take a little) you could use a lower octane rating without any bad effects.
I think I could find the Car and Driver article if anyone is interested, although I am not sure about the CarTalk, but I could try.
I hope this helps.
There was also a CarTalk episode dealing with the same issues and they stated that the altitude of where you live has an impact on rating of the fuel. For example, if you live in Denver (elevation 5'280 ft give or take a little) you could use a lower octane rating without any bad effects.
I think I could find the Car and Driver article if anyone is interested, although I am not sure about the CarTalk, but I could try.
I hope this helps.
Trending Topics
MBWorld Fanatic!
Joined: Feb 2004
Posts: 3,122
Likes: 222
From: Milton/Westport, MA USA
me: 2015 SL400 & 2015 ML400; wife: 2022 GLC Coupe; daughter: 2017 GLC SUV
Originally Posted by pocholin
besides if you really think about it and do the math you'll only be saving about $ 2.70 (at the most) per 18 gallon fill up at the risk of long term injury to your engine, knocking, less mpg, etc (all of this is just the risk).......my 2 cents
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Senior Member
Joined: Mar 2003
Posts: 430
Likes: 0
From: LA
Uber 202
I've never put anything else in my car except for premium gas. I remember reading the manual, it says premium fuel only and if you have no choice but to put in lower grade, it specifically says only put in a minimal amount, just enough to get you to a another station with premium. And also says not to exceed like 3000 rpm when you have ****ty gas in the car. The difference between filling up regular and premium is minimal anyways, only several dollars difference.
Out Of Control!!
Joined: Apr 2002
Posts: 20,081
Likes: 0
From: Chicago
Volvo V90 CC
I read the article at car and driver, if anybody is interested just do a search at C&D
They didn't go much into the carbon accumulation, that long term can yield to much loss of power and efficiency (mpg), plus the risk of detonation and knocking, which in new cars is not a big deal because of the knock sensors but then again if the computer detects knocking it is going to reduce your engine's output which translates into less HP/less performance (retard timing).
I guess people buying a new/good car should be willing to pay the price to maintain a fine automobile, and this doesn't just apply to gas, but brakes, oil changes, and other routine maintenance items.
They didn't go much into the carbon accumulation, that long term can yield to much loss of power and efficiency (mpg), plus the risk of detonation and knocking, which in new cars is not a big deal because of the knock sensors but then again if the computer detects knocking it is going to reduce your engine's output which translates into less HP/less performance (retard timing).
I guess people buying a new/good car should be willing to pay the price to maintain a fine automobile, and this doesn't just apply to gas, but brakes, oil changes, and other routine maintenance items.
