I live in Houston and could only buy regular 87 octane following Ike. I own a 2000 E320 and I did not notice any difference in power, economy or knocking sounds. However, I have now reverted back to super 93 octane as before.

 

yeah, you can run lower octane for sure...no problem

 

There are numerous posts about this very topic. The opinions vary greatly. I don't have a problem paying $3-4 more for a tank by using 91 octane. I do pull into the gas stations from time to time and use 89 octane but never on back to back tanks. I get incredible gas mileage and have never had a miss, hiccupp or any drama at all. My engine purrs like a kitten, even after 170K which I rolled over last weekend.

Equally as important as the type of gas you use is the brand of gas you use. Stay away from the no-name mom and pop gas stations. They are more prone to cheap gas dumping in some states. Water in the fuel, dirt and other nasties can result from using bizarre off brand gas. Stick with the big boys. They spend more money by blending in the detergents which help to keep your injectors clean.

I saw $3.11 / gal reg earlier today, Oct 10th. Amazing!!! I can't wait to pay $3.00 for a gallon of premium. Isn't it sad that we are getting excited about $3.00 / gal gas? Disgusting.

 

Reg gasoline is way under $3/gal right now in Oklahoma....

Kevin

 

I pay $3.30 for regularhere in upstate NY.

 

Run a addittive for knocking. I'm not sure what compression ratio your car has. The lower the octane # the less compression it takes to preignite. Detenation is very hard on a motor due to it explodes before the piston is at the top of it's cycle thus forcing the piston into the rod, rod into the crank, and the crank into the bearings. All when the crank has to continuie to push the piston to the top awaiting the powerstroke which already lost a lot of it's power. One cheap way is to dump a pint of transmission fluid in the fuel tank. This will not help preformance, but will reduce detenation by raising the flash point of the gas.

 

running regular gas will not have any effect on the operation on the engine unless you are redlining the thing all the time. Simply tooling around in a general fashion has absolutely to do with octane...believe me....

 

To low octane will cause Detenation from Idle to red line. It is just not as hard or as noticable.
Dentenation is very hard on the lower end of a motor. Unless you have a turbo or supercharger detenation happens at all rpm,s due to it is the same compression ratio at all ranges.

 

Some 'yahoo -old' boyfriend told me that it would be ok to use 87 octane in my MB 2004 C230Kompressor. NOT! I have been doing it in 2009 mostly to save money... but my check engine light came on... I had a scanner put on the car (thanks to Auto Zone and they used an OBD2 scanner) to find out what the CEL code was... it said 'lean fuel'. I am going back to 93 octane and hope it clears up.

 

That sounds like fear, uncertainty and doubt! (FUD)

If countless Asian taxi drivers run their Mercedes all day on standard petrol, and the Mercedes engine has a knock sensor that adjusts for the octane of the petrol, then talking about using higher octane fuel or buying additives for fear of damaging the engine is illogical. This is the Mercedes Forum, not a forum for discussing brand-x engine that doesn't have a knock sensor.

I have run my 1989-built 500SEL for over 30,000 miles on standard unleaded fuel and never noticed any problem. As for lack of power, well we have a 100 km/h speed limit on the freeway on which I commute to work, so I hardly touch the accelerator! I can't vouch for going flat out, but the car goes as fast as I want it to, without ever flooring it or even halfway flooring it, so that doesn't sound like it's severely crippled or anything, does it? I did test it over 100 mph once, but I don't want to push it (by doing that regularly), because I don't want to put undue wear and tear on the engine or other components. Now, if we had an autobahn (in this part of Australia) there might be some merit in upping the octane, given the potential of this engine. My Dad used to always run 'super' in his 1965 Jag, but what I have been unable to find anywhere on the Internet are any figures that would suggest that one could improve fuel economy (giving ordinary commuting driving) using higher octane fuel, by more than or as much as the additional cost of the fuel!