It's a gas question

Do we absolutely have to use premium gas in our used 2006 E-class Mercedes or can we fill it with regular gas and use an octane additive?

this is a common question on these forums, click the search button and type in “premium”, and see the discussions

Does Your Car’s Owner’s Manual Say That Premium Gas Is “Recommended” Or “Required” ?

A sticker located at the gas cap might also tell you this. I don’t think I’d use an octane additive. Read carefully, you wouldn’t want to ruin a catalytic converter.

Click this link to an article explaining this:
http://blogs.consumerreports.org/cars/2008/07/premium-gas.html

Does your car say recommended or required for premium?

CSA

If your Benz will not tolerate regular, it will let you know soon enough. FORGET additives. Their claims are little more than that, just claims.

A Benz is a display of wealth, a status symbol. You are what you drive. You are expected to maintain that image in the showroom, in the service department and at the pump. It’s a package deal…But 4 or 5 octane points are not going to change the course of history or “ruin” your engine…Damaging spark knock or detonation is a VERY audible thing. If you don’t hear it, no damage is being done. Some claim you will notice a reduction in performance and fuel mileage, but I have never had that experience…

You need a minimum 91 octane. read your car manual. Yes you really need the minimum. If you have to put low octane in for half a tank and then fill with a higher grade. It is all in the owners manual. Thats where you should check.

FOR THE PRICE DIFFERENCE WHY BOTHER WITH A ADDITIVE? USE A GOOD 93 OCTANE GAS AND YOUR BENZ WILL BE HAPPY. PEOPLE WILL ARGUE THAT AS LONG AS IT DOESNT KNOCK USE WHATEVER OCTANE. WITH A 93 OCTANE IT WILL PREFORM BETTER.

HOw many miles do you drive in a month? How many MPG do you get? How many gallons is that a month? At 20 cents more per gallon, how much more will you spend buying the correct fuel than you will trying to “get by” on the cheap stuff? For most folks it works out to $15 or $20 a month. If you can’t afford that, buy a Chevy next time.

Note: I have owned more Benzes than I can remember, beginning with a 190SL in 1968. Most of them (that used gasoline) ran well on premium and poorly on regular.

WHY do you want to gamble with your engine? WHY?
It’s a myth that cars cost less to maintain as they age. It takes MORE maintenance, and costs more, as your car ages.

Repeat after me:

High Octane gas does not help an engine that does not need it. Octane is not a measure of quality or power.

Octane is a measure of how easy the gas starts to burn or how fast. High octane means it is hard to start burning. On the other end diesel is measured by certane and a high certane number means it is easier to start burning.

High octane gas may or may not have more additives like cleaners in it, but with today’s regulations any gas has enough for most engines.


   The owner's manual will say that it must have high octane or that it may use regular but should use high octane.  The parts the leave out are:

  * If it needs high octane, using regular can damage the engine.

  * If it should use high octane then it has a system to sense the low octane and to make adjustments to the car that will protect the engine.  However the adjustments will result in lower mileage (reducing or wiping out any economic advantage) and will reduce the power, defeating the reason most people buy cars that require high octane. 

  * Using high octane in a car that does not recommend it very very seldom causes damage but cost you more.

Assuming you have the sedan E-class, then you have a 20.6 gallon tank(according to Edmunds.com). If you ran the tank dry, you’d spend just a little over $4 more using premium vs. regular. How much does a bottle of that octane booster run? $5? $10? Will you need 2 bottles since you have more than a 20 gallon tank?