Basically, 89 Octane will have the same effect as 87 Octane more or less. Your engine will still retard timing, your performance/power will still be negatively affected, and your mpg will still be less than optimal (although 89 Octane may or may not have slightly "better" performance and/or mpg than 87 Octane... I dunno). However, keep in mind that 89 Octane is still NOT 91/93 Octane and NOT recommended for your vehicle, therefore all other effects on your vehicle mentioned in this thread will still apply more or less.

As for using 89 Octane instead of 91/93 Octane or 87 Octane... IMHO IT'S EVEN MORE STUPID TO DO THIS!!! Most people use 91/93 Octane because they will not have a loss in power or mpg, or damage their engines, or risk voiding their MB warranty, and because it's the octane that MB recommends for its gasoline vehicles. Some people may want to use 87 Octane for the gasoline cost savings (which amounts to $0.20/gal on average). However using 89 Octane acheives NEITHER of those goals efficiently! 89 Octane still forces the engine to retard timing, operate at less power/performance, and have less-than-optimal MPG, and like 87 Octane it still DOESN'T have the additional detergent/cleaner additives that Premium 91/93 Octane does (along with the other disadvantages mentioned earlier in this thread). Not only that, but it really doesn't save you ANY money, since the difference between 89 Octane and 91/93 Octane is on average $0.10/gal (which is an extra $2-$6/week, $8-$24/month, and $96-$288/year)! You'd be saving more by going to Starbucks 1 time less per week!!! You'd be saving more by eating out 1 time less per month!!!

If you REALLY can't afford an extra $2/week, $8/month for gas, then you should just sell your Mercedes-Benz and buy a cheaper used vehicle that takes 87 Octane right now on Craigslist since YOU'RE BROKE!!! Seriously, what are some people thinking?!?!

 

The difference is about >>>>>>> <<<<<<<< that big .. which is a lot.

 

lol browsers won't show more than 1 consecutive space.

 

I love how you can say that everything I say is bull****, but all my sources are sound. Quoted verbatim, from my first source, 6.14
http://www.faqs.org/faqs/autos/gasol.../preamble.html

"If you are not meeting the octane requirement, the engine will rapidly suffer major damage due to knock. Youmust notuse fuels that produce sustained audible knock, as engine damage will occur. If the octane is just sufficient, the engine management system will move settings to a less optimal position, and the only major penalty will be increased costs due to poor fuel economy."

I'm glad you spent your entire career in the oil industry, unfortunately experience and intelligence are not substitutes for each other.

According to Mercedes, they may deny a warranty claim for EXPLICITLY running fuel with an antiknock index under 91 for the following components:

I. Air Induction System
Air Cleaner Housing with HC Trap, Intake Air Ducts, Intake Air Valve, Intake Manifold, CMP Actuator, Variable Intake System Actuator, Variable Intake System Switching Valve, Tumble Flap Actuator, Tumble Flap Actuator Switching Valve, DOR Radiator (PremAir)

II. Fuel Metering System
Fuel Rail, Throttle Actuator, Fuel Pump, Fuel Pump Relay, Fuel Injector, Fuel Filter w/Integrated Fuel Pressure Regulator, Fuel Management System

III. Ignition System
Spark Plugs, Ignition Coil

IV. Positive Crankcase Ventilation
Oil Filler Cap, Crankcase Ventilation Line

V. Fuel Evaporative Control
EVAP Canister, EVAP Purge Valve, Fuel Filler Cap, Fuel Filler Neck Assembly, Fuel Tank Assembly, Fuel Tank Pressure Sensor, EVAP Shut-Off Valve, EVAP Purge Line

VI. Secondary Air Injection System
Electric AIR Injection Pump, AIR Control Valve, AIR Switching Valve, Vacuum Check Valve (AIR)

VII. Exhaust
Exhaust Manifold, Three-Way Catalyst *

VIII. Eng. Emiss. Control Sys. Sensors
Engine Control Module *, Transmission Control Module, 02 Sensors, Engine Coolant Temperature Sensor, Manifold Air Pressure Sensor, Crankshaft Position Sensor, Camshaft Position Sensor, Knock Sensor, Front Vehicle Speed Sensor, Rear Vehicle Speed Sensor, Mass Air Flow Sensor w/ Integrated Intake Air, Temperature Sensor, Electric Accelerator Module

IX. On-Board Diagnostics
Data Link Connector (OBD), Instrument Cluster (MIL) *, DOR Temperature Sensor

X. Related Parts w/ Above Systems
Automatic Transmission Mode Selector
Emission Related: Hoses, Clamps, Belts, Pulleys, Tubes, Fittings, Sealing Devices, Mounting Hardware included *

They can GENERALLY void any warranty claim for "non-compliance with the written instructions for required maintenance and use."

So thank you for telling us all our Mercedes Benz engines will operate with 87 octane unharmed. I'm sure your lifelong experience selling gasoline in Africa means the world to a hundred German engineers who disagree with you and the dealerships who warranty our vehicles.

 

Of course only a mongo would think the anti-knock index is irrelevant to preventing knock. So the next time you feel like using a computer, wear a helmet.

 

Why is this so hard to understand?
Let's assume (incorrectly) for a moment that you will not harm your engine in any way running low octane fuel...

YOU ARE STILL PAYING THE SAME TOTAL $$$ FOR FUEL BECAUSE YOUR CAR WILL GET LOWER MPG WITH LOWER OCTANE DUE TO THE FACT THAT IT MUST RETARD THE TIMING.

You will pay $4 less at the pump for a tank, and then your engine will use ~$4 worth of ADDITIONAL fuel making up for any cost savings.
Don't believe me? Compare your MPG on a tank of 87 to your MPG on premium.

/END OF THREAD!!!

 

Can someone explain what retarding the timing is?
I've only had my car for a little less than a month and was using 89 octane, but I'll use 91 octane now.
That month of 89 octane won't do any damage will it?
Probably only filled it up twice.

 

Your a moron. 1. the manual in the c300 is not top notch. 2. 335i is a b***h car. 3. audi s4 is only 44k try 56k+. 4. 350 is in a different league from those cars. your comparing apples and oranges. the 350 is a n/a motor pumping out a respectable number. And honestly if im gonna get a fast german car its gonna be the c63 not that ****ty bimmer that will fall apart at 30000 miles. or the underpowered s4 that cost almost as much as fully loaded c63.

and op use premium bro. you don't want f**k up your motor just to save 5 bucks. think of the cars gas as food. what happens when you eat junk...

 

Honestly, if you are going to call someone a moron, you might want to learn to spell.
Not to mention the cars you are completely discounting are not bad vehicles...maybe not your favorite, but at least respectable machines.

 

Oh well since I finally posted in this thread I may as well put in my two cents worth.
Both engines are oversquare by a similar ratio, tend to make their power at similar RPMs and are pretty close as far as NVH characteristics. The 3.5 gives you a noticeable bump in power for not too big a hit in fuel economy but a couple thousand bucks costlier. It is hard to argue that the 3.5 is not the better engine but there are a couple costs involved.
Of course, if you love manuals...you only have one choice, but a little more control helps alleviate your lose of power.

 

Just wanted to add that Benz C350 produces 268hp and is a NATURAL engine. On the other hand, BMW 335i and Audi have turbo charged engines... Ever wonder how much faster would be the C350 with a turbo?????? It will beat the sht of the other two.

 

The C350 with a supercharger, upgraded headers and downpipes will produce 350hp

 

You still can't read so I'm not going to pursue this any longer. If you could read you would note from my profile that I'd not spent my career selling gasoline in Africa. I had a global job that encompassed everything from selling lubricants to industry, to working in our & other research facilities to supporting motorsport endeavours including F1. If you can't understand that your original post (your words) was misleading then so be it. BTW - I always had a very fine relationship with the Daimler Benz engineers when I handled OEMs for our company.

Let's just place the facts on the table & drop it.

Benz have a requirement in Europe of 95 RON (90-91 AKI) - what you see on the fuel flap decal. All 272 engines destined for the American market & many other markets where alcohols may be present in the fuel are designated by Benz as, so called, "Flex Fuel engines." Flex fuel engines have their fuel system components designed to accommodate the potential corrosive and other deleterious effects of alcohols. They also have their engine mapping & other control broadened to accommodate a wider range of fuels including those containing alcohols. Alcohols tend to raise RON substantially while having far less of an effect on MON thus effecting the AKI as stated on American pumps. These fuels include E85 which is very high ethanol content & high octane.

I stand by my comments but reiterate that I encourage C Class owners to only run their vehicles on Premium Gasoline.

 

And you're calling someone ELSE a moron?

The 335i and C350 are direct competitors. I can't see how you consider this "apples to oranges" or that the C350 is in a different league. You're in denial, fanboy. Just because YOU bought a C-class doesn't make the C-class the standard bearer. Everyone knows the 3-series is the standard. The C-class is a fine automobile and no one disputes this, but people like you do it a disservice. I expect this kind of attitude on a Civic forum, not on a Benz forum.

Second, the 3.5 M272 does put out a "respectable" number. As does the J35 in the new Accord V6. There are more 3.5L N/A 6-cylinders that put out much better numbers. See IS350. See an older G35 or a new Maxima. Let's not put the 3.5 M272 on a pedestal. It's respectable but there are plenty of naturally aspirated 3.5L V6s out there that do better.

Third, you say the C350 is in a "different league" than the 335i, but then mention the C63? You think the 335i and C63 are competitors? Who is the moron again?

Lastly - I'll say it once more - 87 or 89 octane will cause your car to retard timing. You will lose horsepower/torque and MPGs, thus cancelling out any savings you received from using lower octane fuel. It will not damage your engine. However, if you can't save any money by using lesser octane, why use it?

Period.

 

This thread is out of control! Good info on the octane ratings though.

 

I totally agree with this, while I don't like the BMW's *35 designation, since their engine displacement is only 2979 cc as opposed to the 3498 cc displacement of the Mercedes engine, to say they are NOT direct competitors is definitely off the mark. The idea that BMW uses inline 6-cylinder turbo to bump their engine output 32HP over the Mercedes and the Merc is a naturally aspirated V-6 is a valid argument, but it doesn't make them different classes of cars.

I looked at the BMW 335 when shopping as well, however when I priced out the cars the way I wanted, the Jaguar XF supercharged was a much more attractive car than the BMW. The sticker was $72k but the dealership offered $52k so the discounts on jaguar are huge... and it had last year more features than the E class does this year, plus a 510 hp engine that would eat a BMW's family. Take one for a test drive, they really are quite an experience. The C63 can hang, but not at the same price. Of course, that's because Jaguar is owned by Tata motors in India now. Unfortunately, Jaguar would not accept my trade-in at a decent price, So Mercedes bumped to the top of the list, but not before Jaguar knocked BMW down for the count.

 

hehehe...lol..funny

 

I think it is more than just the engine? I think the brakes are tuned slightly differently, and the front suspension is just a tad stiffer. This is also somewhat due to he larger wheels and slightly lower profile tires, makes it a bit bumpier and firmer.

The throttle response is also tuned differently, and not just the extra HP.

So, the effect that Mercedes was going for, sportier, faster, faster acceleration, slightly better handling, stiffer, more throttle and brake response was most likely achieved.

 

All I know is that, if I had the choice between the C300 and C350, I'd take the C350. In real world driving the C350 is more efficient as well as being quicker. Aside from that, anyone who doubts the N54 twin-turbo in the 1/3/5-35i is .

 

My goodness, 300 vs 350 motor was all it was about, and all this... My two cents, I think the C could definitely use more than 268 horses. That motor is strong at the midrange but not so strong at the low end and high end. It just needs to put out about 50 more horses, like the Infinity V6. I do believe Mercedes has a 300 horsepower V6 in the SLK, why not just put that in the rest of the lineup? I got the C350 because I thought it was the most powerful regular C class. Had there been another C that had over 300 horses and not as expensive as the AMG model, I'd have definitely gotten that, but there was no other. I'd probably end up upgrading to an E class or M class when the lease runs out a year later anyway.

 

Just how i felt when opening this thread right now...shocking

 

But yea guys, let's not try to kill each other over this. The Octane argument was very good, and now im really considering ONLY running 91 in my luxury cars from now on...even if i have to get a night job. Now im feeling bad for my lexus in the driveway...SO i had a question that popped up...as a overall sport sedan/luxury car...which car is a better value with ONLY THE FOLLOWING OPTIONS...P1, 18" AMGs...only options i want.

 

Robust interaction is good for everybody that has an interest in the subject matter. Everyone learns which is the purpose of such forums. If you have no interest then move on to a less technical thread like rearview mirrors or the pros & cons of Obama.

You now know as much as any motorist needs to know about octane as it relates to the 272 engine. This allows you to make an informed choice & I like the way people are thinking.

 

Well said my friend

 

I have a c350 & have had C300 loners. The difference in power is quite noticable to me. Also a bit difference is the engine noise, since the C300 is trying harder to get up to speed, it creates more noise, and you can hear that in the cabin. The C350 is smoother & quieter. However the MPG difference between the two is huge! i got about 8MPG more on the C300.