ssz

I've read about some folks using 89 or 87 octane in their E350s with no obvious problems. Is this reasonable/OK?

dchar

Knock sensors will adjust to the lower octane, but just don't expect to get the full performance from the engine (horsepower and fuel economy). Not worth it IMO.

KEY08

Why?

Lolxa

My 2010 E550 knocks like crazy when idling when there's 87 in it. (I watched a YouTube video explaining that it is all the same. Don't believe everything you see), I just buy 91 now, and its very smooth, with the occasion micro jutter once in a while, but overall alot more smoother than when I put 87 in. Performance and fuel economy wise, didn't notice a difference.

The G Man

You engine will run dirtier with lower octane, not a good idea to run lower than require octane on a direct injection engine.

kajtek1

You can also save money by skipping M1 and fill up the crankcase with cooking oil.
They sell it very cheap in convenient jugs at Costco.

PLINYELDER

Expect a 10% loss in performance, put in the tank what is recommended. There is a reason for that. Some newer turbo cars maintain you can use a lower octane without mechanical issues but performance issues will exist (eco boost motors for example). You own a Mercedes don't skimp on gas.

davidjohnbamber

IIRC my 2014 E350 gas filler door stated that you could use E85. That said, I bought a car designed to use premium fuel.

ssz

Thanks, y'all. I'll stay with high test (91 or 93 octane). SSZ

Peachy

degeja

just alternate 89 and 93 when filling up

tresean1

Hahaha, that is hilarious! I roflmao at my desk; a simple non-verbal "yes, just do it!"

PLINYELDER

No, don't do this ^^^

Lolxa

Never do this, remember the on board computer is making adjustments to reduce knock, if your alternating that means there is always going to be different ratios in the fuel, meaning that your engine is going to knock like crazy.

pjw1967

Your car has a 12:1 compression ration. My '67 GTO is 10.75:1. If I tried to run 89 or less in it, the engine would sound like there were ball bearings rattling around in the cylinders. My wife's '14 ML350 is also 12:1. Might be the same engine as yours (same hp). Inside of fuel door says 91 or more. We don't get 91 here, just 89 and 93. So your heading asks if you can run 91. If you can get it and your fuel door says 91 or more, you're good. Like another poster said, the engine will adjust the timing to avoid the knock you cannot hear to protect the engine. But you will not be getting all the power the engine was designed to deliver.

KEY08

No, iit says less than 91, and then he goes on to ask about "regular" grade gasolines of 87-89. If all that is available in a premium grade is 91, then he has no choice.

pjw1967

Thanks. I missed the <.

degeja

Wow such precision in gasoline octane levels and the car computers.
Am amazed,

The G Man

How much are you really saving by doing this? Say 89 octane is 15 cents cheaper a gallon than 93 and you fill up 3 times a month on average and 36 times a year. Half of the fill up in which you use 89 you will save $2.70, that comes out to $48 a year. Hardly worth the time or the effort.

KEY08

^ bingo!

raja777m

Before getting into luxury, I told myself many times, "Premium gas, Higher maintenance costs, Don't expect reliability if I r*pe the crap out of it".
I don't even wanted to take it to Costco to save those 20cents per gallon.
I promised myself, Shell, Exxon, Mobil1 or BP; premium only, else, I won't buy the car for myself

So, I joined fuel rewards network from Shell, and Plenti from Exxon/Mobil1(if in case) for some perks and cash back.

SteveE400

First question. . . WHY? If the MB engines run anything like my 4.3L V8 Lexus did you will save about. . . NOTHING. There were user tests run with the Lexus LS430 using both regular and premium fuels. While the regular was cheaper per gallon, users found that the engine management systems de-tuned their engines (although imperceptibly) to use the lower octane, WHICH RESULTED IN LOWER GAS MILEAGE. The lower mileage just about offset the reduced cost per gallon, resulting in almost identical cost per MILE with either fuel.


BTW, faja, if you read the Costco Pledge, they pledge to distribute only Top Tier gasoline, which is technically equal to any of the brands you mentioned. I've been using Costco gas in two MB's over the past few years and it is fine.

Airmousam

^^. Me too, no issues ever with sams club fuel

raja777m

Did anyone did tests on Costco/Sams/Kroger/Safeway Premium against 4 leading brands, for performance, MPG etc.?

How much will it cost to run such tests, since, it is worth it, if it is less price, I'm ready to invest on it.

Similar to this:

subzero05

I use 89 on a regular basis and never experience any issues.