BobbyT

What are the effects of using regular gas in current Mercedes?

Considering that modern engines have knock sensors and engine management systems that make required corrections when knocking occurs, there is probably some corresponding minor reduction in performance. Other than that, are there any long-term negative effects?

drpasteur

i use Premium only

Polar Bear

This is very debatable. The cleaning effects of premium fuel are typically much better than their regular grade counterparts, so premium will keep your engine cleaner and running better overall.

Mercedes designed the engine to run on premium fuel, and therefore the published specifications for economy, performance and horsepower are generated using premium fuel.

For what it's worth, there is an ignition timing setting in the ECU that can be adjusted by the dealer. Every 2008 and 2009 vehicle I have looked at had this set to 87 octane. On one car we changed this to 93 octane and noticed a difference in performance in stop and go traffic (the car felt more responsive) and a noticeable increase in fuel economy.

The owner was of course running 93 octane fuel.

In the end I think premium fuel gives you better economy, and better performance so I think it is a wash in terms of savings you would save by using regular fuel. Plus, you will keep your engine cleaner.

Vik888

What model car is it?

Basically, as someone else already pointed out, 87 will give you crappier milage and it will void your warranty. You might as well put 91 and get the better milage and performance.

Lastly, why buy a Mercedes if you can't afford the gas? Get a Camry .. better milage, you can fill it with **** and it'll run forever. Heck, I saw a guy do his first oil change at 100k miles .. the oil was like mud, but hey saves you from changing the oil! There you go -- no expensive fuel, no oil changes even!

E200turbo

I think engine management and knock sensors on the newer Mercedes models are good enough that no damage will be done with regular. Check your owner's manual to see if premium is required or just recommended.

I get better gas mileage with premium but not enough to pay for the higher price that premium costs. However, I also didn't fully test this. I only tested it between 90 and 93 octane and mostly between 91 and 93 octane.

If you are really cheap and live in an area that sells 92 or 93 octane, you can mix regular and premium gas to get 91. With 92 octane, use 80% of that and 20% 87 and you will have 91 octane in your car.

Chevron, 76, Phillips 66, and Conoco says that their additives package is the same concentration in all grades. Shell says that they have 5 times the required concentration in premium and 2 times the required concentration in regular.

For better mileage, add 3 psi to the tire pressure listed on the door jamb. Mercedes says in the owner's manual that 3 extra psi is recommended for better handling and fuel economy. The posted tire pressure is for better ride.

Untertürkheim

Use premium, if you can't afford the gas, buy a different car. A search would have answered your question:

https://mbworld.org/forums/s-class-w...gular-gas.html

Polar Bear

In every US gas model I've owned the manual says it's required, and even says if premium is not available to use the minumum amount of regular required to get you to a station with premium fuel to fill up, and to avoid fast starts and not to rev the engine above 3000 RPM on the way to get premium. They are pretty clear in the manual that they don't recommend it.

It may be different in other countries.

drpasteur

true, if u gonna get a Mercedes and can't afford premium gas...then get Camry.

Polar Bear

He is asking a legitimate question and was looking for some reasons supporting Mercedes' claim that premium is needed. No need to recommend Japanese junk to him.

My friend just bought a 2009 C300 and the dealer told him (without him inquiring) that the car will run fine on "regular gas" and that it would not hurt the car. This came from an MB dealership. Perhaps this guy's dealer told him the same thing so he is researching it.

drpasteur

don't you know that 80% of the salesman people and even sales manager don't know **** about the cars they are selling? i had experiences where salesman just read off what is listed on that paper listing the features and MSRP price

Polar Bear

Yes, I completely understand that. And I do all of my own research before I buy, find the car I want and buy it. I even bought my own SDS because the dealer service department could not fix a glitch with my car even though it is still under warranty, and fixed it myself. Trust me - I understand that more than most.

Untertürkheim

Add in the fact that they will say anything they think will sell the car.

My SA told me that MB now checks the cars and will void the warranty (or not honor it) if the car is being run on less than 95RON 91R+M/2 octane / premium fuel.

dvmak

I'd stick with premium. Relying on the knock sensors to compensate the timing will not prevent long term 'damage' to the pistons.

vettdvr

If the car is tuned for premium I would use it. Mine specs 91 octane. I use 93 most of the time. However after Katrina and Gustov fuel was what ever they had at the pump. Regular ran out first and only premium was left. Then the premium sold out and the reg. filled up first. Week or so later premium would arrive. So I have run regular in our E500 that is tuned for 91 octane. The owners manual states you can do this at reduced performance. So when we have reg in the tank we NEVER use more than 1/2 throttle. This is also what GM states for my Corvette. Basically if we don't have prem. we use what we can get but we accomidate by reducing the loads on the engine to prevent any damage. Granted the knock sensor on the corvette and MB should compensate but we can also compensate by not pressing the accelerator as much. Damage to the cars,, none. Warranty is still good also. The MB dealer in hurricane area understands that sometimes it is either regular or NONE. Given this choice we have been known to fill up with regular but when Prem is available we will immediately add to what ever is in the tank.

Now for running reg all the time. NO,, I didn't buy performance cars to drive them as gas sippers. Fair mpg is ok with me and the corvette delivers 27 on the highway and the MB 25. So these are ok with me and I always buy prem. fuels. For ethanol I avoid it like when I can. Our gracious previous gov. (name deleted to protect the incompentant) signed into law all fuel must have ethanol, but the I guess between baking cakes she was an engineer also.

lkchris

What can "Mercedes claim" possibly mean.

They are the folks that designed the engine.

It's not a claim, it's a specification.

Internet geniuses have nothing to add to that.

Polar Bear

You obviously didn't take the time to read the post above...

I was pretty clear that regular is not recommended.

Aren't the dealerships the ones that says you can't install SAT radio in an a 2006 W211 after if it didn't come with it? Xenon headlights? Phone? There's a lot of misinformation going around at dealers and even MBUSA - THEY can't even answer a question correctly sometimes.

He asked a simple question and not whether he should buy a different car... Responses like the ones that are in this thread discourage people from participating in the forums.

Barry45RPM

Running regular will NOT void your warranty. Mechanically speaking.. aside from compression ratios... why would you be able to run a Toyota engine on "****", and a Merc engine would require Premium only or you're going to destroy your engine and "void your warranty". That makes as much sense as "Elvis is alive living & in retirement". Your engine computer can compensate for less than ideal fuel.

Your MB engine will run on regular, with reduced performance and milage due to the engine computer retarding your engines timing to avoid knock or pre-detonation. Simple as that. The question remains though... why pay for all the performance and then willfully do away with it? However, the unspoken question may simply be that since September 15th 2008, many people have to spend less money, and since they already own the car, are merely inquiring if saving money might hurt the car & cost more money in the long run.

My Dad (an old Dude, who likes the Brand, but has no idea there are even options available in a Mercedes), doesn't know the difference between performance levels when using Premium VS Regular. As a matter of fact, he's always used the cheapest grade of no name Regular in all his MBs (...just like every rental car out there), and he's perfectly happy. His cars go at least 10 years before he "freshens up" his ride.

You pay - you zoom... you save -you cruise. In some places theres a 25 cent difference in the price between Regular & Premium.

vettdvr

Zoom Zoom for me and I pay the price,, wait a minute isn't Zoom Zoom another car commercial.

220S

What PBear, Kent, and Unterturkheim are trying to get across is that sure, the motor will fire on "regular" octane, but the performance, life, and costs of operating that motor are optimized for "premium" octane.

The bottom line, imho, is that there's no reason to try to use "regular" unless "premium" is just simply not available.

However, it is available just about everywhere. And yes it costs more. 100% octane fuel also costs more. But the reality is that your engine's performance and mileage does improve with higher octane fuel. I often mix "premium" with 100% octane (available here at some 76 stations) in my P-car. I actually get better mileage with that mix. Throttle performance is also better.

The reason I put quotes around "premium" and "regular" is because those terms are simply relative words depending on the octane. And octane varies in geographic regions. The OP lives in CA. I also live in CA. We have low octane gas here in CA relative to the rest of the world. Premium gasoline is even more important here, imho.

The only reason to use "regular" is in trying to be frugal. I applaud frugality in these economic times. However, you are really doing a disservice to yourself trying to save a bit by using "regular." In the long run, "premium" will save you money.

If you are leasing and couldn't give a s**t about the car and have no ethics about eventually having that car being passed on someday to an innocent bystander, then just do what you feel is right for you in your life.

This topic has been discussed ad nauseam in just about every car forum on the internet.

omegadoug

My car runs fine on 87. But it runs better on 93, and gets 5-10% better mileage.

dvmak

The cars will run on any of the available octane's .. and the knock sensor will compensate. As previous posters have pointed out .. the degraded performance and higher gas usage at lower octane's probably more than offsets the savings. What about additional wear? For most average drivers probably will never realize it .. but the poor schnook buying your used car is getting screwed if he is led to believe you really maintained the car!

To deviate slightly from the topic, I think another point is not just the octane but the 'quality' of the gas your buying. There are big differences in some of the cheap stations some premium brands and the detergents they add.

As for passing inspection in NJ? Unless your car has serious problems (oxygen sensors, MAF .. etc) the gas deviations alone will not cause it to fail inspection even though the car is producing more emissions!

fortlaudsummer

Sure, you can run the lower octane but that doesn't mean you should

Untertürkheim

The way in which the ECU compensates (enrichment, timing retarded) generates less than ideal combustion, which can cause damage to various components.

MB can and will void a warranty if there has been damage caused by ignoring any of the part specifications for the vehicle. Oil, fuel, coolant, etc. It is very easy to tell if the car has been running on less than the required octane.

Boulder GT3

I'm not sure I agree. I've seen several high compression engines with the heads off that had been running regular. There was no pitting or damage in the combustion chamber. This includes turbo Porsches run on the track with regular gas. Current engine management/ECU's are pretty quick at protecting the motor via multiple parameters. I also don't think MB would dink you on warranty claim if regular gas did do damage. I just don't think they have the intelligence to prove it. Further, in many cases, if the motor has internal damage they replace a long block anyways as it's cheaper for them.

Having said all of that, I'm astounded how crappy the winter blend gas is and how bad most higher performance cars run on regular. If you hear that light thready crackle for a second pulling away from light it's your ECU rolling the timing back.

The short answer is run premium from a name brand and not someone buying spot. Still not a sure thing but the odds are better.

220S

Wow. that's a new one on me. At all the tracks I've been at (well, okay the three tracks: Buttonwillow, Willow Springs, and Fontana) the big deal is to run high octane (100+ or VP racing fuel, etc..) Why would anyone want to track a TT running low octane? And more than one? As in TT Porsches? Racing on regular? I just don't get that. Clue me in.

And are you saying that these P-cars were running on the track consistently and then you saw the heads off? Over what length of time, etc? Curious minds want to know. Thanks!