All Mercedes models, no matter the model or the segment, require premium unleaded gasoline. 91 octane is the very minimum acceptable by Mercedes dealers and service shops. This is mostly because premium gasoline greatly increases the chance that the Mercedes you are driving will last a very long time.
Some car manufacturers don’t require you to use premium gas, but Mercedes and many other premium luxury brands do, as premium gas usage will benefit you in the long run.
Modern-day Mercedes engines are fairly complex, packed with loads of different sensors and electronics. To ensure proper efficiency and cohesiveness, premium gas is a must. Many customers have reported that if you use regular fuel in your premium-gas-rated car, the check engine light will eventually turn on.
Difference between high octane (premium) and low octane gasoline
Octane rating is mostly associated with the time it takes the fuel to reach the ignition stage. Premium gas is not necessarily a better-quality fuel, it’s more about how fast the fuel ignites. Lowe- octane rated fuels will ignite way sooner than high octane rated fuels, and higher-octane fuels generally have a higher resistance to pre-ignition.
Newer Mercedes engines have a higher compression ratio, which means that the engine creates higher precombustion temperatures. Some car manufacturers use engines that do not create such temperatures, and that’s the reason why they are rated for regular fuel.
If you use regular fuel in your Mercedes engine (which experiences higher pre-combustion temperatures), it might actually hurt your engine and cause engine knocks due to pre-detonations. It will also lower your fuel efficiency, so there is absolutely no reason for you not to use premium unleaded for your Mercedes.
Regular low-octane fuel usage in a Mercedes
By this point, you should be well aware that you should not use regular gas on Mercedes cars, but, if you do, this is what is going to happen.
When you start to use regular gasoline, nothing will happen, but only in the beginning though.
There is a big misconception out there that is mostly thanks to the terms “premium” and “regular” gasoline. Most people think it means one gas is literally premium or better, while the other one is just regular or normal. But the terminology does not quite convey the right message. There is no “premium” quality increase necessarily, the only true difference is the pre-ignition resistance.
So, if you do use regular gas in your Benz, you will probably experience pre-ignition, also known as pre-detonation. You’ll be able to hear it if listen carefully. The engine makes a knocking effect, and it does not sound as cohesive as it usually does.
Premium high-octane fuel usage in regular fuel rated cars
But what if it’s the other way around? Let’s say that your car is rated for regular low-octane gasoline. If you do use premium gas in such an instance, you will virtually reap no benefits. The only thing that is sure to happen is the pain you will cause to your wallet.
AAA estimates that drivers waste as much as $2 billion per year using premium gas on non-premium gas rated cars. People think that they are taking better care of their cars by using premium gas, but the truth is that they are just wasting money.
Gasoline and wine have very few things in common, but in both cases, people think that a higher price should dictate higher quality, but that’s simply not the case. If you are unsure about the gas that is recommended for your car, check the owner’s manual.
“Premium gas ensures higher power output” is one of the most common misconceptions about premium fuel. The fact of the matter is that engines with higher compression ratios are usually premium branded engines that, in fact, make more power than the engines that require regular fuel. But the fuel itself makes absolutely no difference.
Facts to know about premium gas
How much more does premium gas cost?
According to AAA, premium gas costs as much as 60% more than regular fuel, or even more in some cases. Premium gas costs more due to higher levels of pre-ignition resistance, which means that the fuel itself is far more refined compared to regular fuel pre-ignition resistance levels.
Premium gas costs more due to environmental reasons as well. Premium fuel costs more to make and to refine. Furthermore, the laws of supply and demand also dictate that premium gas should indeed cost more money compared to regular fuel because regular fuel-rated cars are a dominant majority.
How dangerous is engine knocking?
Engine knocking is the effect of the fuel and air mixture igniting itself due to higher engine temperatures, and not by spark plugs. This effect usually happens at the same moment that the spark plug itself also ignites the fuel and air mixture. So, essentially what you are getting is two different explosions in the cylinder, instead of one.
If this persists for a longer time, there is a chance that the pre-ignition might actually damage the pistons, even severely in some instances. Both the price and the inconvenience that are associated with such an event are extremely high. So just use the rating recommended by the manufacturer, and you should be absolutely fine.
What if I accidentally put diesel fuel in my gas-engine car?
You might think that such accidents don’t happen too often, but sadly they do. Is come countries like the US, where gasoline is the predominant fuel option, this does not happen as often. Gas nozzles are usually a different color compared to diesel nozzles, and they are also differently shaped for these specific reasons.
But if you do accidentally put diesel in your gas car, do not drive it. Call a mechanic right way. Even though it may seem fine at the beginning, that’s mostly because you will still be driving on the remaining gas in the fuel system. The diesel probably hasn’t yet reached the engine itself.
Diesel is a lot thicker compared to gas; this means that the pump itself will struggle to pump the diesel into the engine. Furthermore, the filters will also make it harder for diesel to reach the engine itself. So, you will most likely just end up with a clogged engine. Don’t worry, though, your engine won’t explode or anything like that.