Lynn

tcmo, you might also call Tri-Star Imports in St. Louis (actually Ellisville) for their advice also. I find it outrageous that the dealer in Columbia wants you to do something harmful to your car. You might want to call 1-800-FOR-MERC and let them know what is happening.

tcmo

My father lives in St. Louis so the overnight stay is no problem if Plaza needs to keep the car. The dealer in Columbia is the one who told me to try the 89 octane. I contacted Plaza by e-mail with my concern but have not heard back.
Lynn, of the two dealers mentioned (Plaza and Tri-Star) who would you recommend for service? I purchased my car at Plaza because they had a car close to what I wanted and gave me a much better deal than either Tri-Star or our local dealer-Legend.
Thanks.

mdp c230k

The most likely cause is one or more faulty ignition modules. They are solid state devices and as such can be temperature sensitive. Often transistors can function fine at 75F and not work at 70F due to thier junctions no longer making contact. This is usually due to breakage due to thermal cycling, but not always. These transistors also can function fine at higher temps like when the car warms up. There is also a certain amout of 'infant mortality' in these units. The easiest way to test for the problem is to use freeze spray on the suspect parts. If they crap out when sprayed you have your answer. I'm sure the dealer should know this, if not get out of there! By the way, the 89 octane wont help. Hope this explains a little..

Lynn

tcmo, I have heard several positive comments about the Plaza shop, and only one serious complaint. That will happen with any shop. I have heard about the same comments about Tri-Star. Plaza is much easier to get to, since it is right off I-270. Go ahead and use that shop.

The reason I bought my car at Tri-Star is that I was ignored when I first walked into Plaza, and then treated poorly when I dared interupt a sales monkey's reading of the newspaper. Tri-Star was very attentive and wanted to sell me a car. However, I may use the shop at Plaza, because they seem to be competent and they are much easier to reach.

tifosiv122

This is in response to an older thread where people stated the used less then the 91-92 octane. I posted this new thread so it would call attention to correct octane.

https://mbworld.org/forums/showthrea...threadid=32076

I just got something from MB today to remind me of their services....inside was a FAQ:

"Shop Talk"

q: Do Mercedes-Benz vehicles have special fuel requirements?
a: For all Mercedes-Benz gasoline engines starting with model year 1987 (if you have an older model please consult your owner
s manual), use only premium unleaded gasoline. When fueling your vehicle, the octane number posted at the pump must be a minimum of 91. By following these fuel guidelines, you'll help preserve your vehicle's durability and performance.

q: What should I do if only low-0ctane fuel is available?
a: If you unleaded regular is available, use only the necessary amount to get you to a station thathas premuim unleaded gasoline and fill up there. Another thing you should do when you get behind the wheel is avoid accelerating quickly and driving at full throttle. If your vehicle has a light load (two occupants and no luggage), keep an eye on your engine speed - it should not exceed 2,000 rpm. If it's fully loaded and/or operating in mountainous terrain, refrain from moving your accelerator pedal beyond two-thirds of its full range.


If anyone wants me to scan the FAQ or the entire document, please let me know.

Erik

x15jq

I ran my car with a full tank of regular. I went above 2000 rpm and nothin bad happened

But, there was no super availabe where I went so I decided once cant kill it. I didnt notice a performance loss, but does have worse MPG, due to ignition anti knock retard.

IOBH

Deaker told me I could use 91 octane but recommended 93 when I bought the car. What does everyone else use? Its about 10 cents a gallon difference in GA between 91 and 93 octane.

2004 C230K Sedan Brilliant Silver

Tai230K

the manual says 91 is min, in NY we don't have 91. Well i haven't seen it, I use 93 or 94 octane.

trench

They're tuned to run on 91 octane. Adding anything above this is pretty much a waste of money (unless you don't have an option like Tai230K) as the car isn't going to change it's timing curves to take advantage of the excess octane. Changing these curves is one of the ways chip companies like Powerchip, etc. can up the horsepower, by tuning the car to utilize the extra octane.

MikeSL5

91 is fine but dont go lower cuz then you'll have engine problems. They said the same thing for my 2003 Navigator. The service guy said ppl bring em in for engine problem and it was a result of not using 91 gas.

r_liebo

Some general thoughts on high Octane gas. Most cars don't need anything but regular -- despite what the manufacturer says. I can't speak of the Merc (since mine isn't here yet). But I switched from 91 octane that BMW insists upon as a minimum to 89 octane with no problems or noticeable loss of power on my 325ci. So, then I tried plain old regular 87 octane, and still no problems or loss of power

A recent study done by consumer advocate Clark Howard, including conversations with Porsche mechanics and engineers, concluded that all of their cars will run just fine on regular gas, despite Porsche's company line of "premium fuel only". Most high end car manufactuers have very cozy relationships with particular oil companies (see Mobil 1 oil propoganda as an example).

I very seriously doubt any manufacturer would build a car that MUST run on 91 octane or suffer damage (think about the quandry a driver would be in if they accidently put in 87 one time, or the gas station was out of 91!). The only symptoms you may exeperience by using lower octane gas is a minor loss in performance due to any extra knocking the engine must eliminate.
So, you could try the lower octane and see what happens.

Then again, perhaps these Mercedes engines are different from BMWs and Porsches, and you must actually use such expensive gas. Perhaps someone here can post their exerience using plain old regular gas.

Lastly, if you have chipped your car, you may need to use the higher octane gas to get the full benefit of the chip.

jpb5151

Don't these cars electronically adjust to lower octane, resulting in lower performance that may or may not be noticeable to the driver?

Anyhow, we use 93 here because it's the same price as 91 at other stations. A couple days each week, the price is even lower.

There was some test article comparing the different octanes but I can't remember where it was, nor even which of the MB forums it was posted in...

Lynn, help please!

Junbug

Does anyone here know whether we have knock sensors on our C230K?

Thanks

trench

Often times the reason people experience lackluster performace with MB loaners is because people are cheap and only fill them up with 87 octane. I remember someone complaining how sucky his loaner performed, but then refilled it with premium and saw a great improvement.

Lynn

Yes they do.

Robert Schrader

Does the 320 have them?
Thanks

TNblkc230wz

All modern engines have at least one. Most V engines now run two. Some high performance engines are running one per cylinder.

Outland

Forced Induction engines, like the Kompressor(Supercharged) ones in our cars, run much closer to detonation than does a naturally aspirated car such as the 325. Its in your best interest, from a mileage, performance, and engine longevity standpoint to use at least 91octane in such an engine. Will it run on 87? Obviously, the answer is yes. Will there be a trade off, also obviously yes. The knock sensor will just keep pulling that timing back...and you'll be at the MB dealer so puzzled why that supercharged C230 SPort Sedan engine doesn't feel any stronger than a C240. And If youve got a 2.3L Kompressor with a pulley and run low octane fuel, you should ask yourself why you spent money on the pulley.

Its not who makes the engine. Its not the type of gas. Its not the electronics. No mystery...no special tricks. A higher compression naturally aspirated engine will also benefit from higher octane fuel...but not the same way as a forced induction engine does.

Junbug

Thanks Outland!!! I was about to post a similar message.

r_liebo

I guess there is a noticable difference with the supercharged engine. I'll be trying all levels of gas in my c320, to see what difference I feel in performance and/or gas mileage.

Outland

Its unlikely you will notice any difference with your C320, as it uses the MB 3.2L V6, a naturally aspirated engine that is very mildly tuned. Owners of the M111 C230 Kompressor Coupe, M271 C230 Kompressor Coupe, C230 Sports Sedan, and the AMG C32 should all run high octane fuel. The C240 and C320 likely won't even notice the difference in fuel.

C230 Sport Coup

Pretty much in the time I've owned my c230, I've just run the cheapest premium I could find.
I mean it's all the same right?
I had a lady friend years ago that worked for Shell, and that what she used to say.
It's especially true in the Bay Area, where ALL gasoline comes from the refinery in Martinez, in the East Bay.
And all most all of it has MTBE in it.

Now recently, I noticed that 76 was about the same price as the cheap ****, like 5 cents more. I decided to treat my baby.

Now 76 doesn't use MTBE anymore. So they stand alone, with a different formulation, using Ethenol Achohol instead.
Likely around 10%. Overall this is a little better for the environment, and if you catch a whiff of the exhaust it does seem to smell a little different. I have an older car that when I take it for smog, I mix 20% alchohol in the gas, and it's a guarateed pass, so for certain it also reduced emissions.
Yes, emisssions are a function of the fuel going in.
Just think if we put it in all the gas. Less emission, less pain in the *** passing smog.....

But what I've noticed the most is that car doesn't hesitate at all anymore. No lag time at the pedal.

I haven't decided if it's just in my mind, or for real. But as as fac ts go, it is a different formulation that all the other MTBE gas around.
And my Butt dyno tells me it's worth the extra buck at fill up.

What do you guys say? Anyone note a performance increase, or for that matter, decrease in power based on the brand or formulation of the fuel?

now I'm talking California, where we're stuck with 91 octane premium. So pathetic.

Buellwinkle

Used to work for 76 and I can tell you that yes, unbranded fuel coming out of the pipeplines is generally the same but not exactly. 76/Tosco has it's own refinaries, Chevron has it's own, Mobile has it's own, so I don't understand why someone would tell you that it all comes from one refinary or one terminal, it doesn't and different refinaries refine to different standards. For example, drinking water, it's all the same right, so why buy one brand over another? Yet people do have favorite water brands because they do taste different yet they are all 100% water. Then there are federal and state mandates for additives that all fuel companies in CA have to comform to and then there are local mandates like in So Cal for additional additives. Now there's an issue of MTBE vs. Ethenol, the problem I see is what happens if they mix, could it cause problems? Also what are the long term effects of Ethenol, will it cause problems with gaskets, deposits, etc... Lastly they have trading partners, for example, 76 does not have a terminal in Hawaii, so they buy their fuel from Chevron and the additives that brand it as 76 are added on the truck. Then in reciprication Chevron may buy fuel in places they don't have a terminal like Alaska where 76 moves a lot of fuel.

So then the question is what's different, why is one gas better than another? In the U.S. Octane ratings are an average of 2 different octane methods use in other parts of the world. Different refinaries will produce fuel that favors one over the other but still ends up with the same average octane number you see posted and some cars do better with one vs. the other. For me, I've notice that Shell and Arco do worse in my motorcycles (pinging) than Chevron and Mobile so I tend to favor those brands. It's truly hard to tell on modern cars because they don't ping because of the slight variation in fuel. Also, while most additives are government mandated, some are put in by oil companies to make their fuel better. These companies advertise the fact, like Chevron with Techtroline (or whatever it's called). No oil company other than the ones that advertise otherwise put any additives other than what's mandated by the goverment.

Personally I stay away from Shell/Texaco (one in the same now), ARCO and gas stations brands that don't refine their own fuel (Thirfty, Costco) as they just buy whatever is cheap that day. I tend to stay with Chevron 1st, Mobile 2nd, 76 3rd.

amdeutsch

Are you saying that the 10% Ethanol blend has the same Octane rating as Premium? And it costs more?

Here in the Midwest we see quite a bit of this fuel. Usually its blended with Regular but because of the Ethanol it carries an 89 Octane rating versus an 87. Price difference is usually only 1 or 2 cents higher than Regular.

A 10% blend is fine. Only when you get to higher blends, like 85%, will you need to have a specially designed fuel system in your car because of the corrosiveness.

Buellwinkle

Are you reffering to the M85 (85% methanol/ 15% gasoline) they run in the midwest, that's different, runs in special C320s. Here they are using the ethanol instead of MTBE with some brands of fuel as an oxygenator to reduce smog. The advantage of ethanol is that it's non-toxic like MTBE and doesn't contaminate ground water, no other reason. Many people believe these oxygenators don't really do anything (other than raise fuel prices by a huge percentage for us). The advantage is minute on old cars with poor smog controls, newer cars with smog control show no difference in emisions with these reformulated fuels. I wish they would just drop it and spend the money on something more effective.