My mom put 87 Octane fuel in my Mercedes instead of 91 while borrowing my car last week...

My mom put 87 Octane fuel in my Mercedes instead of 91 while borrowing my car last week. I've since been averaging about 5 mpg over the 16 mpg I was previously getting, and so far haven't noticed any performance drop.

Can anyone explain why this is happening? I assume it's due to the knock sensor modifying the engines power output but it seems to be just as quick as ever.

How old is the Mercedes?
Engines in OLD Benz cars love cheap bad gasoline

Really though, any car made from... say before 2004, Premium is a waste and should stick to Regular

Jesus. What a bagger.

I'd hit that, amazing body and she still has a pretty face.

You obviously have no idea how gasoline works.
You should ALWAYS put whatever octane the car requires. The only reason not to would be if a station doesn't have the octane you need.

>pretty face
Pretty fucking square

>put whatever octane the car requires
Except for the fact that as a car ages, gains wear inside the engine parts, and deposits of carbon and possibly slight sludging of oil up in places where only a rebuild can find...

You're not likely to get the benefit of higher octane in older worn engines.

Ergo, wasting money on High Octane fuel in an engine that's aged and doesn't get that benefit is STUPID.

Noob

Tell me, in your fun little world what octane means.
Because in the real world, octane is the resistance of a fuel to burn, not amagical number that keeps your engine cleaner or gives you more power.
Higher compression engines NEED a higher octane fuel to work efficiently. If they don't get the fuel they need, they will knock and if the knock is not accounted for, they WILL fail catastrophically.
Please, learn something before talking out of your ass. Premium gasoline has NOTHING to do with engine sludge or wear on an engine.

You're an fucking idiot. Premium gas is a fucking meme. Modern ECUs can adjust themselves to run on lower octane fuels just fine. Even if the car requires premium, it will run just fine on regular gas and save you a ton of money. Unless you're going to a race track or some shit, you don't need premium gas.

Yeah, they'll adjust by pulling timing and giving you less power and more wear on internal components.
You won't save a ton of money unless you're working a minimum wage job, in which case you shouldn't be driving something that requires premium.

Holy shit, did Veeky Forums go retarded or has it always been this way?

>less power
A few hp doesn't matter on the street.

>more wear
Cars go hundreds of thousands of miles on regular gas just fine.

>hurr minimum wage job
Just because you make more money doesn't mean you can't be frugal.

Yes, they CAN go for a good amount of time, but you're running on a measure meant to protect the engine in the case that you can't find the right octane.
If the engine is recommended to run a certain octane, you should stick to it.
You will not only get better mileage, but more power and less wear on internal parts, plain and simple.

Don't believe me?
When the ECU pulls timing, the "boom" in the engine happens earlier before TDC than it would otherwise, creating more horizontal load on the rod bearings. Over time, this extra force will oval out the bearings, requiring earlier replacement than if you had just used the right fucking gas. Engines aren't tuned to run on whatever you can find on the side of the road. You can only target a certain efficiency, and if the efficiency set involves a certain variable (octane and detonation angle), it is in the interest of the engine to keep them as they are.
It's really not a hard concept, but I could explain the difference that just a bit of extra sideways load on the bearings has.

* to clarify, the tangential force on the rod bearings is not extra, but it is a larger amount than would have otherwise been directed at that angle.

>oh no ill only get 500k miles out of my car rather than 550k :(((((((((((

What does a 1995 Miata require? I normally put 95 RON, and 98 RON every few weeks. I only put 91 if I'm super broke.

Not sure about RON, but regular is fine for that engine.

...

ugh, whos right, i almost felt stupid for filling my 02 is300 with 91

yeh mayng 07 es350 many ppl say regular is fine, the new es350s with the same engine no longer require premium, toyota uses similar (not exactly the same) v6 in camrys etc. which aren't premium

dayum homie only way to fine out is try dat shit i gezz

lol get the lowest octane. does Veeky Forums even read the manuals

>When the ECU pulls timing, the "boom" in the engine happens earlier before TDC than it would otherwise

No, wrong. The ignition is timed so that maximum chamber pressure is reached just as, or shortly after the piston reaches TDC. When you use lower octane fuel, the ECU adjusts timing to prevent the combustion before piston is at TDC.

I wish that minecraft looking bitch would build me a sandwich

Do whatever the manufacturer recommends. One tank of regular won't kill you but always go with the manual.

you dumb bastard