Just bought a 05' C230 Kompressor Sport for my wife.

Please dont laugh at me for asking which grade fuel to use? or is OK to use.. gas tank says premium, but what octane is best or use-able? I know we cant use un-leaded 87.

Most stations have 93-octane, but there are quite a few here and around the out-skirts that only have 89 (Mid-grade)..

Would 89 (mid-grade) be ok to run in these? I know that running too low of octane can detonate the pistons and super-charger, I usually use 93 in all the vipers and vettes I work on...

Just trying to know so I can tell my wife what to and what not to use.

Bieng a diesel guy, im used to cetane ratings..lol, not octane..
Thanks!!

 

93. your car won't explode if you use 89 but it's DEFINITELY not suggested to use it long term

 

91 octane. Anything more is a waste. Anything less reduces engine output (although I bet you couldn't tell).

 

Lower octane and low quality fuels will cause carbon build up. Mercedes does not allow gas or oil additives except in very narrow circumstances. The additives must be from the approved products list as well. My take is that premium fuel is by far cheaper than an engine. 91 is the minimum. Only cars that have E85 on the label by the fuel cap can use that fuel. Here is the fuel page from the manual:

Technical data
Fuels, coolants, lubricants, etc.
Premium unleaded gasoline

To maintain the engine’s durability and performance, premium unleaded gasoline must be used. If premium unleaded is not available and low octane fuel is used, follow these precautions:
• Have the fuel tank only partially filled with unleaded regular and fill up with premium unleaded as soon as possible.
• Avoid full throttle driving and abrupt acceleration.
• Do not exceed an engine speed of 3000 rpm if the vehicle is loaded with a light load such as two persons and no luggage.
• Do not exceed 2/3 of maximum accelerator pedal position if the vehicle is fully loaded or operating in mountainous terrain.
Fuel requirements
Flexible Fuel Vehicles (identified by a label reading Premium gasoline or E85 only! on fuel filler flap) are
designed to operate on premium
• unleaded gasoline or ethanol fuel (E85) or any mixture of these two.
For more information, see “Flexible Fuel Vehicles” (> page 433).
Only use premium unleaded fuel:
• The octane number (posted at the
pump) must be 91 mm. It is an average of both the Research (R) octane number and the Motor (M) octane number:
(R+M)/2). This is also known as the ANTI-KNOCK INDEX.
Unleaded gasoline containing oxygenates such as ethanol, IPA, IBA and TBA can be used provided the ratio of any one of these oxygenates to gasoline does not exceed 10%; MTBE must not exceed 15%.
The ratio of methanol to gasoline must not exceed 3% plus additional co-solvents.
Using mixtures of ethanol and methanol is not allowed. Gasohol, which contains 10% ethanol and 90% unleaded gasoline, can be used.
These blends must also meet all other fuel requirements, such as resistance to spark knock, boiling range, vapor pressure, etc.

 

According to the FTC: "As a rule, high octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car's engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car."

 

i thought of this too, but think about this... if you spend 3.25 on mid grade, and 3.35-3.40 on super.. even on the highest of that difference, and say you fill up when the low fuel light comes on

youre spending .20 more per gallon over 14 gallons, which equals to a massive payment of 2.80 more per fill up... to me, 2.80 is a price ill pay to ensure im not spending 5k on a new engine with labor


not talking about you specifically, but people get crazy about gas prices going up .05-.10 a gallon.. unless youre filling up constantly and have a huge tank, its not really that big of a difference

see, now i had a truck with a 28 gallon tank, that got 10mpg with mostly highway driving... now THAT makes a difference, but only because i used more MPG

 

You already have a car with an engine that's borderline junk. There are issues with carbon buildup on valves where dealers replaced heads under warranty, there's issues with rubber vaccuum hose disintigrating that forced a recall, there's issues with cam sensors leaking causing thousands of dollars in damage and some years are affected by the valeo radiators that destroy transmissions. Do you really want to add another risk that will make this ticking time bomb go off any sooner than it has too. Stick with good name brand premium (91 or better) gasoline. The exta few pennies are worth it. What is it anyway, 10 cents on a $4 gallon of gas, so 2 1/2% more? Get one of those credit cards that gives you back 5% towards gasoline purchases, you'll be ahead.