Buell says:
Personally I stay away from Shell/Texaco (one in the same now),
++++++++++++++++++++++++++++++++++++++++++++++
I for one have always been a big fan of Chevron and there additive Techrolien.....or however they spell it. Even other brands sell the additive in a can so it must be good....right? I also like Union 76 but around here they are always the highest.

Perception is everything and if you've lived in California for any length of time you might remember when the cleanest, most modern gas stations around were ARCO and the gas was touted as being among the best. Then they went budget and only self-service and while sales increased there perception of quality has decreased. In my business I come across people from all professions and one was an executive for ARCO. During our visit we talked about there gas and he claims no body has a better additvie for keeping your engine cleaner than theirs. And that unlike many stations they use the same amount of this additvie in all their grades of gas. Still...........I don't use it very much even though the car seems to run fine on it.

There are a lot of stories out there about gas and so on but one thing I've found to be true. As Buell says 'all gas in California (maybe the whole US) has to meet certain values like octane'.

The difference is the other stuff or lack of. All gasolines have some cleaning agents but some only meet the MINIMUN standard while say Chevron, Union 76, Mobile and Shell go much further.

Lately I have switched to Shell. The price is right and they have reformulated there premium gas and claim higher mileage. So...I tried it and you know what? There right.

I have been going between Chevron and Shell now for almost three months and EVERY time my mileage for the whole tank is higher with Shell. Not by much most of the time but ALWAYS higher and sometimes by as much as a full mile per gallon. Long trips, short trips.......doesn't seem to matter. I mean ALL the time. Has to be something to it....

Best of all. I have a Shell that's showing it's bottom line to two other stations on the same corner. One sells Chevron and other Mobil. The Shell station has been uncutting them about 5 cents a gallon now for months and is really pushing out the gas. Couldn't be better for me.

 

Once again Buellwinkle is not entirely correct. Through most of the country gas from ALL major refiners is shipped down the same pipes. If you put in X gallons into the system you are allowed to take X gallons out of the system at a distribution point. It may be gas your company has refined, it may not. All gas put into the system meets a standard level of properties. At this point it is all the same. The difference comes when each companies additives are introduced locally. The additives are what makes each brand of gas different.

 

Minor correction here Carl. We got E85 (85% ethanol / 15% gasoline) here in my neck of the woods. And actually it runs in most automatic C320s. The exceptions here would be no 4-matics.
Cons of E85:
Less BTU in E85, drop in mpg up to 20+%
Pros of E85:
100 Octane, no loss of performance, costs about the same or less than regular gas, some states allow a personal taxcredit (i.e. $750 taxcredit if using 500+ gallons within a 13 - 23 months period depending on first registration of vehicle and availability of E85) on a 1 for 1 basis without having to file the long form. MB doesn't charge anything for this capability unlike the big 3 in most cases.

 

It's hard to argue with someone that hasn't been directly involved with this aspect of the oil business so I'll try to explain it in simpler terms. If you work for an oil company then check with the people there, you are misinformed. The "pipelines" are rented by oil companies for a block of time. If they miss that time slot then they don't get fuel. For that reason, some oil companies will frantically drop their prices below costs to clear some terminals for their time slot, not something they want to miss, that's where small time operators like Costco get their savings, by shopping the price every day. The previous oil company's fuel is cleared out and dumped into transmix and the oil company's fuel is then sent through the pipeline. Never is any oil company's fuel mix other than to dump it into transmix and sold as such. Then fuel is then routed from the pipeline to the oil company's terminal. You can speculate all you want but 76/Tosco refineries produces 76/Tosco branded and unbranded fuel, it was never refined and put into a 76 terminal by anyone else. That doesn't mean that 100% of the time when you get fuel at a 76 gas station, it was refined by 76/Tosco, they have trading partners in different markets like I've mentioned before but then it's picked up at the partner oil company's terminal and it is unbranded fuel and then mixed at the truck, it's not the same fuel that the oil company sells as it's own. Also oil is traded on the commidities exchange, so if 76 has extra diesel for example, it can go to the commodities market and dump huge quantities there.

So while the refining process is basically the same, it's also different and some cars do better on one brand than another. There is a difference, it's not one big pot that all oil companies draw from. Also most oil companies, 76 included put the same exact additives as other companies, these additives are not secret forumulations, they are government mandated. Some do add additional additives but when I worked for 76, they did not.

 

What mdp c230k says is EXACTLY what the woman I dated said.
It's all the same up to the point they add the addtives and the other thing she used to say was the amount of additives was so negligible as to be completely insignificant. Like a drop or 2.

 

Some women believe that. Actually some of the mandated oxygenation formulations run 5-7% additives and even 10% as someone previously noted with ethanol and that not only varies from state to state but in CA it varies from county to county and from season to season.

 

Quite true.
I knew her before oxygenated fuel.

 

Im a cheap skate and ever since i bought my car i have used 89 octane and i believe the car says i should put 91. is that bad for my engine what i have done? I finally have money to spare now to use 91 octane is it safe to change to?

 

I doubt it would do any harm. The rental cars don't get much better gas than minimun and it doesn't kill them. Our modern ECU's and knock sensors should be able to adjust to the gas used. But just wondering how much difference in money is there between the two grades???

 

I doubt there is any damage. There was an article in USA today about gas grades and someone from MB said that if you don't use premium, you will probably not achieve the specs listed on the car, IE, horsepower. But the difference is so small, you won't be able to notice it. The ECU and knock sensors in todays car's are able to adjust to what kind of gas you put in.

Sometimes my folks use 89 and other times 91. I can hardly tell a difference in power. Feels just the same.

The price difference wise, sometimes on a tank of gas, it can range from $1 - $5 difference here and if your tight on gas money, it can make a difference.

My .02

-G-

 

Given the "looming" gasoline crisis as the local (northern CA) rag put it, I thought I'd ask the SOAK on this forum what is the straight skinny in using, say 89 octane, instead of 91 premium?

I realise you would probably take a hit on milage, but any other effects? I assume the electronics are capable of making timing adjustments for the change in octane, but how drastically can you push it? 87 octane?

 

Using 89 is fine. The onboard computer will adjust timing for the grade of fuel so that detonation does not happen. I believe that you dealer can actually set it to take 89 as the standard, but don't quote me on that.

You may take a hit on mileage or not...I've seen various results. Some lose a few miles and some others don't.

I'd say throw in a tank of 91 every few tanks for good mixture if your going to use 89 for now. I feel ya on gas prices, MA just broke the $2 barrier for Premium (93)...it's at $2.09/gallon now just almost everywhere. Some are still $1.99/gallon.

 

Making the ECU retard the timing so you can save a few bucks is your call. Detonation is back for the Engine and can and will cause problems later. Before the ECU can retard it has to sense detonation in the chamber first, so even if it is retarding that means it is detonating as well, although not as bad as it could. You will also cause other issues but I am not sure what they all are. All I know is if you get detonation in the chambers enough you could pop the engine. So think about what is better, saving a few cents a fill up or putting in a new engine at your cost. MBUSA will be able to tell that Detonation has occured and they can read the ECU for codes to tell them what happened. So warranty can technically be void on the engine and drivetrain. It is your call, but the engine was designed for Premium Fuel.

 

I think the minimal amount of money you'd save would not be worth the risk of damaging your engine.

Let's say you save 10 cents per gallon, you use 15 gallons to fill up, and you fill up 4 times a month.

.10 * 15 * 4 * 12 = $72 in savings per year.

 

That was much shorter and a better point than I made. Thanks....

 

Thanks for the input. I understand the math and did the calculation prior to posting. BTW, its more than a delta of $.20 here. Cheapest 91 is $2.46/gal.

Increased cost/warranty issues aside, I'm interested in the mechanical ramifications of using 89.

BTW, $150 buys 2 bottles of Lagavulin a year.

 

Because the ECU has to pull back timing and enrichen the mixture, specially in the summer heat to make up for the lower octane fuel, the 5% you save will be more than eaten up in higher fuel consumption. Penny wise and dollar foolish. If you really want to make a difference, trade in your fuel hog for a Toyota or Honda hybrid....

 

it has been shown before that using a grade lower (93/91 to 89) doesn't cause detrimental effects to the engine itself. There was a study done using engines that *required* premium and it was filled up with regular, so even less than what you want to put in, then opened up the engine to compare with a identical engine using premium. It showed normal wear when compared to both of them. But, of course, it's to be taken with a grain of salt.

this topic has been beaten to death so many times :p

the manual also even says to use regular when premium isn't available, just don't go full throttle if your the *grandma* type driver, there shouldn't be any problems IMO.

 

This would be the case if the engine is normally aspirated. A supercharged plant will have extensive problems (ping, poor mileage/performance, HEAD GASKET) and could even have detrimental and expensive effects over an extended period of time. The only manual "suggests" you can use non-premium fuels IF premium is not available....but I interpret that as a temporary measure, not a solution to high gas prices.

 

Someone on here once posted a link to an article wherein MB made a statement regarding this, the availablity of fuel availability in different parts of the world, etc. The result was admittance that the engines could run on lower Octane fuel, at a slight loss of power most likely not very noticeable by the consumer, without detriment to the engine.

 

yes, there was an article published on this a few months ago when they did a study on cars requiring premium and what would happen if they used 87 or 89 instead of premium.

result was loss in a few HP (which more than likely the consumer will NOT notice unless they put it on a dyno to see the results) and gas mileage may possibly be affected by a few miles.

MB came out saying that if you don't use premium, you will not achieve the horsepower specifications that go along with your specific vehicle.

Porsche recognized that there may not be premium available everywhere in the world where they sell their cars so they said that their vehicles are able to run on regular as well with no problems.

For non-N/A engines, yes, premium should be used, but my understanding is that the supercharger is not engaged unless it deems necessary, right? So if you drive light footed, I don't see a problem with using 89. no?

But it's not our car, each and every owner has the right to do what they please.

 

Exactly, that's my point, you'll just lose a few MPG, so the 5% (10 cents) you save at the pump is nothing compared to losing a few MPG or 10%-15%. So in an emergency go for it. As for losing unnoticeble HP, that depends on the car. If you have a small 4 cyl motor that is supercharged/turboed you will lose big time, on my car, the 2.3L motor, someone tried it on the dyno and lost 19 HP, not trivial by anyone's standard.

 

Come on, are you that close to the knife-edge of solvency that saving a buck or two on a fuel fill will make a real difference to your life? Why on earth do you have a Mercedes then?

I agree with Buellwinkle - look at a hybrid car or better still a direct injection diesel like a Jetta TDI, or in Canada, the smart fortwo cdi. The latter does over 75 MPG US on the highway and ~ 60 in the city. Plus it's a cheap car (about 14K US for the convertible).

I'm getting one in September, a cabriolet, and I will have a laugh at the expense of people in gas hogs as they despair when regular gas hits $1.50 per litre here in Canada

 

ok...everyone thinks that just because you drive a MB doesn't mean that you can/are obligated to spend money just like that. Yes, you can afford the car, but what if after the fact that you are having financial troubles? or on a tight budget? Does that mean that you shouldn't be driving a MB or driving at all?

It's been shown there have been no detrimental effects on using 89, let alone studies have been using 87

One of the studies used a brand new '03 BMW M3 and they filled it with regular the entire time for a long term test using 87 vs the recommended 91/93. They checked out the engine and it looked like what it should be from normal wear.

Ok, what about countries that don't have premium (91/93) and they drive a car that recommends premium? What are they to do then?

 

I think this is spot on. It really would be risky for a big time car manufacturer to design vehicles that would risk engine damage on 87 octane gas. It would be a PR nightmare when cars started breaking down here in the U.S (MB has enough reliability issues as it is!).

I have used 87, 89, and 93 octane at various times in my C320. I haven't noticed any power difference, but I do get better gas mileage with 93 (about 1mpg difference).
Not an expert in this area by any means, but I think you will feel more of a performance difference with the c230.