DCApilot

As you all know, Mercedes recommends the use of premium unleaded fuel in the 2006 ML. Even the owners manual contains recommended operating limits if you have to put less than premium unleaded into the tank. My question for everyone is does 92 or 93 octane fuel really make that much difference compared to regular 87 octane unleaded fuel. I have a friend who says that it's more marketing by the fuel companies to get you to pay more for the gas while not really doing much for the engine. I on the other hand believe that you get what you pay for and the engine will be better off with better fuel. Anyone out there know the real skinny on regular vs. super premium gas and what the short and long term affects are, if any, on the engine? Thanks for the insight.

vraa

It's not marketing. Your engine will retard the timing, and you'll get less gas mileage.

Trust me, you're not saving anything (maybe 75 cents) over a tank compared to premium versus anything lower after you factor in gas mileage and what not.

CE750

There is a WORLD of difference in low and high grade gas, not the least of which is the Octane! Then there is the additional additives such as found in Chevron gas (Techron) that keep the engine clean.. these are usually dosed higher in 91/93..

Tell your friend if he has an MB drop the Walmart attitude and pump 91RON into it (unless it's a diesel like mine).. forget the $.20/gal cost savings BS.

Or put it like this.... being a turbine driver you know that most Jets can run AVgas for a short time (or in many cases for a limited number of gallons).. but they "Recommend" Kerosine... we'll 87 octane is AVgas, and Kerosine is 91..

Chi500

Premium gas contains more detergents, which help to clean out the carbon build up in your engine. Different companies have different formulas. The ones with the "best gas" are referred to as top-tier companies recommended by car makers such as BMW. Your Mercedes will run on pump gas, but you will get less power and less gas mileage, defeating the purpose.

E55AMG99

OMG! Not this AGAIN? Do some independent research. Too many people here have proven they don't have a clue about gasoline. BTW, it isn't a marketing gimmick. It is highly regulated. Start by reading this FAQ. Sure , it's long but it will explain everyting you need to know about gasoline.

http://www.faqs.org/faqs/autos/gasoline-faq/part1/

CE750

since IMHO, you know more about gasoline/fuels than anyone else I've come across on this board, and since you seem to agree with the rest of us.. I think DCA can take it to the bank that it's more than "hype".

CE750

BTW... I find this quote interesting from your FAQ E55..

E55AMG99

The FAQ was compiled over a few years and has not been updated for almost 10. However, it is an excellent primer as most of it still applies today.

Greg
P.S. Thanks for the compliment

Militant-Grunt

Since I have done experimentation and a whole project on this...

Like mentioned before, 87 octane will give you lower mileage, and retard engine timing. In case you dont know what retarding the engine timing is.. It is when the ECU adjusts for lower quality fuel so that engine knock isn't caused. As lower octane fuel will cause engine knock in engines that require gasoline with a higher compression rate. ( hence why you need premium.. ) Engine knock causes your engine to over heat, and over time it will cause major damage to the cylinderhead, as well as other engine components. ( Engine knock is when the explosions within the cylinder happen too early ) Like I said there is retarded timing to prevent that, but it is still not good for your engine.

So unless you want to save yourself major repair expenses in the future, get better gas as it is only a buck or two difference.