the manual states premium fuel is needed I wonder what your thoughts are on this..... i've heard it can affect you catalytic converter or is this a rumor, with the cost going up everyday I really need to know

 

There ARE reasons why the cats go bad (and that seems to be a relatively frequent occurance in the MBs), but I seriously doubt any of those include the use of premium fuel. In my opinion, you are going to do much more damage to your engine by using less than 91 octane.

Hopefully, some of our resident experts will add something more to this thread.
M

 

These engines have knock sensors to protect the engines

* with the high compression ration 10:1 - pinging or spark knock can cause damage to the piston tops, ring lands or valves due to localized hot spots

* MB doesn't want additives being put into the gas tank - so by specifying premium grade, you're getting higher detergent gasoline by not buying grade 87 octane stuff.

the owner's manual state that if you have to buy lower grade (less than 91 octane)

* don't fill up completely - buy enough to get to the next stop and fill up on premium - drive more moderately until a full tank of premium is filled up.

* use less than 1/2 throttle while using lower grade. avoid heavy engine loads, steep grades

* no full throttle starts with less than premium grade

With all those cautions, I would stick to what the maker recommends.

 

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What exactly do you mean by additives Hal? Do you mean octane boosters or something like the Chevron product Techron, which is supposedly in their gasoline that we buy, or that we can also buy separately?

For what this is worth, they recommend adding a bottle to the fuel tank every 3000 miles to help keep the injectors and valves from carbon build-up.

M

 

I use premium fuel 91 octane (Cali Blend) all the time due to what MB recommends besides whats an extra 3-4 dollars on gas anyway for a full tank when we spend $3.50 a gallon.

 

Actually, premium is a relative bargain these days. When regular was a dollar premium cost 20 to 30 cents more per gallon, a 20-30% difference. Now that regular is around $3 premium is still 20 to 30 cents more per gallon, or a mere 6-10% difference. And, it is getting easier to find a cheap gas station that sells premium for less than an expensive station sells regular.

 

How does the California formula differ from the rest of the country? If I remember correctly, auto manufacturers used to make special "California cars" to meet your stricter emission requirements.

Also, where are you guys finding 91 octane? Except for the off-brand stations, all I see is 93 (the next lower is 89).

 

I hadn't thought of it that way. The grades have always been about 10 cents apart as far as I remember.

What gives me an ocassional chuckle, is that diesel USED to cost less than regular-grade gasoline, but I've seen it selling for about what premium does these days.

 

I encourage people to read their owner's manual about that topic - it does address it. I think that MB doesn't want owner *****-nilly dumping in chemicals into the gas and then having problems with fuel system components getting damaged (seals, fuel sender contacts, injector seals/pintles or injector coils, or fuel pump assemblies) as there are many additives out there, some better than others.

One thing I recommend is to visit this site: www.toptiergas.com - it addresses the problems of deposits that other manufacturers have observed with low detergent levels in gasoline. I wouldn't recommend trying to save a few cents a gallon on low quality gasoline only to have to spend more $$$ in the future to have engine deposit issues that might require more intensive work to remediate and would offset the minor savings in buying "cheap" brands of gas that skimp on detergents that may prevent deposits from forming.

I use the Techron concentrate 2x a year AND use the top tier brands of gas -because throttle body carbon build and intake valve deposits are regular maintenance issues (as well as keeping injectors from getting deposits). On my other (non-MB) car, I do this same routine as well. I also saw this mentioned on MotorWeek's TV program a couple times in the past as well.

I always notice the car idles smoother and has better response since I've been doing the 2X/year treatment for the last 4 years or so now.

That car doesn't have a MAF sensor, but I do manually clean the throttle body (I'll have to see how easy it is to access the one on my CLK - that car has about 34,000 on it now after 5+ years) and if it needs it.

 

In California we've had winter oxygenates added to fuel since the mid 1980's and then had various formulas of oxygenates that were specific to the areas that didn't meet CARB (Calif's version of EPA) or EPA standards.

The along came MTBE until they found it would pollute groundwater (leaky storage tanks in gas stations or leaks in pipeline systems) so that was phased out about 3-4 years ago.

In CA, Methanol is used in varying proportions (up to about 7% I think) as well as other additives to meet the RFG requirements in CA - so our premium grades average 91 octane around here (used to see 93 a few years ago). So our grades are 87 - 89 - 91.

The CA emissions - a lot of other state have adopted the CA standard (MA, NY, NJ and some others) and some manufaturers have just gone to a 50 state certification using the CA standard which had the lowest emissions levels.

Made it easier than making a CA, high altitude, and then a 3rd version beyond those other two former standards. Fewer versions to configure and certify for the EPA - the HP and mileage ratings are uniform across the board now.

In the past, there were a number of engine transmission configurations that couldn't be sold as new in CA going back to the 70's.

We still don't have new passenger car diesels sold in CA since the '99 model year, but that will change when the low-sulphur fuel starts coming out.

 

I'm with you 100% on these suggestions. I've only put 7000 miles on my E430 in the last year, so I guess I've added Techron Concentrate 3 times in that 12 months. I ALWAYS use Chevron Supreme 93 octane too.

During the last "B" service, the tech put a can/bottle of something into the fuel tank, and I've forgotten to ask the dealer:
1) what do they use?

2) did my car just need it or is this the MB "problem preventative and every ~20k standard procedure"?

Thanks for the input.

 

I don't know what the might have added. Some shops (this was mentioned in the most recent issue of MBCA's The Star) will add chemicals to boost their bottom line margins in revenues. Especially if the customer is paying the bill...

There may be "approved" DCAG additives or if symptoms indicate certain conditions might exist.

In the past the mid 80's to mid 90's MB's were prone to carbon build-up clogging EGR passageways if the cars were not driven very much annually or a lot of stop and go driving. They would have problems not passing emissions tests or other drivability problems.

The best thing to do periodially is to operate the car at highway speeds fully warmed up and drive with tranny in 4th (or 3rd if conditons allow it) to get the combustion chambers hot enought to slough off carbon build up. This way you can safely do this routine and observe speed limits by getting the engine into the higher RPM band (don't need to go to redline). Always make sure fluids (coolant, oil level, power steering) at proper levels and hoses are in good condition before putting more stresses on systems on the vehicle.

Not WOT, but a part-throttle cruise (for lean operation) at normal operating temps for 30-40 miles to have it 'self clean' as it would do at Autobahn driving conditions when you have open roads. Our US roads and congestion patterns often have us driving a low speeds, which encourage carbon build up at a faster rate. You'll get slightly less fuel mileage doing this, but done 1x/month will be negligable.

One of my other observations is the MB maintenance schedule calls for spark plug replacements a 4 or 5 year intervals (unless you reach 100,000 mi before then) due to low milage driven each year. This depends on the model year of the car...consult the WIS schedule for your model (or owner's manual?)

This is probably due to soft carbon build up that occurs on the plugs with time.

 

All I have ever seen is 91 but I do remember seeing 93 a few years back, and I don't know the difference between Cali and the rest of the states.

 

My Mercedes Mechanic told me to ALWAYS use the highest octane gas available, and to use ONLY BP gas.

 

I used to use BP too, and still would if I couldn't find a Chevron. In my opinion, all of the name brands (BP/Amoco, Shell, Exxon, Sunoco) are superior gasolines. I simply prefer to have all of my gasoline charges arrive together, and on the same monthly bill. Around here, there are as many Chevron stations as there are anything else.

I became picky about brands when some of them started using ethanol around here (Chevron was one that never adopted that additive). Ashland Oil used to own an ethanol plant here, and they also own the only local refinery, so a lot of our stations started using that. That ethanol plant is now closed, but their gas STILL has it, and so do several of the others.

HAL H in CA mentioned that some of their gas has METHANOL in it (horrors!). That stuff called Dry Gas, I think it is, that treats water in your tank uses methanol as at least one of it's ingredients. I don't think that's something we want in our tanks if it can be avoided. I certainly do not.

Just my .02 cents worth,
M

 

Premium all the way for all MB 1998+ models. It Protects CAT, Fuel Injectors, and Keeps your engine oil clean for a longer period. Besides once it is used to premium, you can not switch back, the car will terribly !! Alos, keep in mine that 91+ Octane and higher burns slower than 89 and lower. In fact higher octane lasts longer in your tank. Why go cheaper.

 

Always use premium fuel from Chevron!

 

Now that ethanol is the only EPA approved additive, all brands have 10% ethanol. The spot price this week for ethanol was $4.00 per gallon. Is that cheaper than the gas they are putting it in? The ethanol will absorb water and thus can not be mixed and stored prior to delilvery. The ethanol is mixed as the truck is filled. One issue with the ethanol is that it will absorb water while in the gas station's tank so a station that doesn't sell a lot of premium gas can have a higher moisture content. Another issue with ethanol is that it can eat away at the gas station's older fibreglass fuel tanks and can cause a leak - that will create a fuss like the MBTE fiasco. Time will tell whether ethanol is any solution to the fuel costs.

 

I see that you are in Texas. According to an Ohio Chevron employee, they NEVER adopted the ethanol additive/substitute. The guy might not have been telling me the truth, but I began using their gasoline because of this.

It used to be a federal, or state law, that IF a gasoline contained ethanol it was supposed to be prominently displayed on the pump (percentages too I think).

I buy Chevron gas in our 3 surrounding states (Ohio, Kentucky, and West Virginia) and I have NEVER seen this "warning".

Furthermore, I know a guy whose job is a blender at our local refinery (Ashland Oil in Catlettsburg, KY). He also told me that "ethanol containing gas is being sold at certain stations in our region, but they no longer make it and it is being trucked in from somewhere else". He mentioned Exxon as having the most stringent blending and additive requirements - but NOT ethanol.

So, my concluding comment is that maybe in TX, what you stated it true. But, it doesn't seem like some of the other parts of the country are using ethanol exclusively.

 

Only a handful of major cities with smog problems (Houston, LA, etc.) switch to the cleaner burning blend during the summer months. (some use it year round and others just in winter) As Hal and Jim noted, this year the additive happens to be ethanol instead of MTBE for the reasons discussed above.

The pumps here in Houston prominently display "contains 10% ethanol". Since it must be mixed at the terminal, ethanol just adds to the already inflated price of gasoline.

Whoever failed to give gasoline refiners protection from MTBE litigation really dropped the ball IMO ... just a terrible time to implement this policy with gasoline so expensive.

 

from what i've read is that it can ran on 89 or 87 and have no problems....although i mix 89 and 91 but i heard once you chip the car then you would have to run 91 since it comes de-tuned out of the factory

 

I live in Israel , here we have 2 kinds of unleaded gas , the regular is 95 octane and the premium is 98 octane.

on my car I have a manufacturer sticker to fill out a minimum of 95 octane, but premium is prefered.

at the dealer they recommand to put into the tank once every 10000 km (about 6250 miles) , a fuel injection cleaner made by "LIQUI MOLY" which is made in Germany.

 

Thank you yoram611,

Wow, 95 and 98 octanes! Sounds like you run your Benz on something akin to jet fuel

I wonder if your octane levels are measured in the same way as ours are here?

Our gasoline manufacturers supposedly use the R+M/2 method, and I have forgotten what the R and M stand for. I also know that there is another method of computation, but I don't think I EVER knew what it was, or where in the rest of the world they use it.

Thanks for the info about Liqui Moly - I'll try to find out how to purchase it.

 

Hello again,

I just found the Liqui Moly website, and it looks like they make 5 products that they categorize as Gas Additives: Valve Clean, Jectron, Fuel System Cleaner and Intake System Purge. The 5th is a concentrate to be mixed with petrol, and then apparently used in an apparatus that flushes out the fuel system under pressure.

Of the first 4, do you have any idea which one we are talking about?

Thanks,
M

 

hi musikmann ,

on the can is written : FUEL INJECTION CLEANER , the part no. is 2902

on the description they write :
cleans the injectors without removal, restores performance and drivability , reduces pollution and fuel consumption , eliminates hard starting, rough idling ,
poor throttle response , lean surging and excessive exhaust emmisions.

this can is made for the Israely market because the writing is in Hebrew and in English , I am not sure if the part # is the same all over the world.

about the octane I know that in Europe they even have higher octane then 98 especialy for high performance cars with high compression.