Gas is ridiculous, and I'm not trying to spend a fortune here. I have a 1987 260E, the book/dash asks for premium fuel, but is that necessary. will regular do?. I know that the compression ratio and all that effect what fuel it takes but will it effect the car. the book says that if lower that premium fuel is used to not go above 2k rpms, but that gives me a top speed of 45 mph. while at the same time I don't want to spend money, I'm not trying to kill my car either

premium is a must but some have gotten away with mid grade.

do what the book says

What he said.

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95 SL500 Smoke Silver, Parchment 64K
07 E350 4matic Station Wagon White 34K
02 E320 4Matic Silver/grey 80K
05 F150 Silver 44K

You could probably get away with lower octane gas, but why second guess the engineers? It only add a few more bucks to the fill up anyway. What if the engine did get harmed? Would the repair bill be less than a few bucks? Nope.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

As was said, the owner's manual for your car should address this issue for your specific car. I believe cars with knock sensors can generally get away with this a little "better".

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

Spend $62-$70 on a diesel fill every time. The you will know fuel price pain.

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Current:
1985 300D aka Miss Margaret
1991 300SE aka Alarice
1995 SL320 aka Samantha
1997 K1500 Silverado
Past:
1999 E300 ex-wife got it and let her son ruin it
1984 190 2.3 ex-wife got it and let her son destroy a great car
1985 300D (CA version) aka Maybelline lost to deer at high speed.
1981 300D aka Madeline (went to salvage at near 400k) rusty, yet best car I ever drove
Wishlist:
McFarlan TV6 (only a few privately owned)
ReVere with Rochester engine
1917 Premier (only one left)

Yeah quit complaining. Diesel costs quite a bit more than premium. And you WILL destroy your HIGH PERFORMANCE HIGH COMPRESSION MB gasser engine if you use regular. It will cause knocking and pre-ignition, slowly killing the engine. Premium is a must.

Not only would regular hurt the engine, it'd also get a lot worse MPG's because it would be running poorly....which would probably end up costing you more than running the correct fuel in the first place.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I got cheap and started putting midgrade on my 99 C230 Kompressor once in a while the check engine light will go on.....months later the O2 sensor gave. It was a $600 repair bill.


97 C 230 OZ racing wheels, Sport interior
94 C280 Brabus Mono 4 whls, Bose Pkg
82 300D Turbo ( my 1st W123 & 4th dsl Mbz)
81 380 SL Sold
99 C230 Komp Sold

You have a little bitty 156 cubic inch engine that gives your car performance similar to an American car with a much bigger V8.

You have a high-performance engine.

High performance in this case is achieved by high compression, which means premium fuel.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

The cost of the high grade fuel is not a limiting factor in owning the car

if you fill up with premium it will cost a little more but you will not end damaging the engine or engine related components, also you will achieve a better fuel mileage than if running on the low grade fuel.

in the long run it will not be as bad as constantly blowing O2 sensors or even damaging the pistons(which retail for over $1000 a set!)

All gas is high and premium is the "Best buy" It's only a quarter more today. Years ago when gas was only a $1.50 it and premium was $1.75. You didn't complain about the extra 25 cents. Now that regular is $3.50 premium should be .75 more or $4.25 , but it not still a quarter more. So looks like you are saving 50 cents on every gallon of premium. Let's hope Exxon doesn't see this thread

I wondered same question. I have an 86 190e 2.3-16. Its not my DD anymore, hehe. My 97 civic gets my nof these days!

89 190e 2.6 on a diet of reg unleaded and even passed Va emissions . Save the hi test for my GrandNational

OK, I'll be the lone voice here.

We have a 1990 and a 1991 124. For all their lives I have mixed 50/50 premium/regular. I figure mid-grade is 89 octane, and my 87/93 mix makes 90 octane.

In the 400,000-plus miles between these two cars, at 10 cents a gallon or so difference, I've probably saved over $2000.

Never any serious engine work that had anything to do with fuel, but I did lose an oil pump once on the 1990 due to the carelessness of a mechanic who dropped a ball socket into the engine. Years later it finally broke thru the oil pump screen and locked up the oil pump.

Both cars have always averaged about 22 MPG.

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2012 E350
2006 Callaway SC560