Question for 300SE owners
 

New to MB gas models, Does the 300SE use high octane like the 420 and 560?

Anybody have any good Pros and cons to a 300SE while we are at it? Im hoping to look at one tomorrow.

we use mid grade in all of our w124's.... sometimes go to premium during the hottest summer periods.

I've been running regular in mine with no issues. Haven't tried it in warm weather though.

I always use premium in my MB's, they seem to run better overall. Occasionally, I'll buy a tank of 89 octane and I can sense the difference under heavy acceleration. Buy the w126, 300SE, you will love it as a freeway cruiser. Biggest adjustment for me driving my 1991 300SE was the second gear start and 'slow lumbering' off the line. If I have a need for speed, I turn to my 94 E420.:) Let us know the outcome of your 300SE decision! A picture or two would be nice.

According to MB, premium gasoline was required in all (non-diesel) US models as of a certain year. I believe that year was 1986 but it might have been 1985 (can't remember exactly).

I think the split was 86 and 87. Our 1986 190e 2.3 does NOT require premium. My 1994 E320 does.

I am not sure if the premium requirement was across the entire model line up, but it may have been.

My 300SE (1989) requires Premium, but I use regular and it runs fine. Gets between 18-21mpg (70% Freeway, 30% City)

I looked at and test drove just about all the different post 1986 w126ers before I finally bought the Mercedes I have now.

I like the look of the short wheelbase sedan, I think it is sexy compared to the other LWB SEL models, which are more stately and formal looking..

They have a LOT of pep for city driving, maybe they have a good rear axle ratio or something. They are highly satisfactory for city and everyday driving

Once you are cruising at 65-75 mph they feel just fine. The only drawback I found with them, was the lack of power for high speed passing and kickdown at 45-60 mph, they were much slower than the 420 and 560. In sum: Generally nimble for city driving, and leisurely on the highway but a good solid cruiser when up to speed. They will be more economical on gas than a V8 but gas mileage should not be a prime motivating factor in selecting a W126, these cars are heavy, solid, durable, safe, long lasting LUXURY models, not econoboxes.

The 6 cylinder engine is a VERY excellent motor. VERY long lasting if well taken care of. Give them a long and thorough look before passing on one.

The manual on my 85 380SE (V8) says to use 87 octane which I do. nor problems, etc. I have put in 89 and 93 but notice no difference. I have put 14,000 miles on it using 87 no issues.

The engine in your MB probably has a gasoline engine with higher compression ratio, and closer tolerances than run of the mill engines. Thus the engineers specify Premium Fuel for optimum performance. However, they realize that some owners will mistakenly use the wrong octane fuel and protect the engine with a knock sensor. Knock is pre-ignition. When a knock is sensed the timing is adjusted by the computer , but the knock already happened. Now your driving with less than optimal timing. Not a good thing.

I can't understand the financially logic that trades 10 or 20 cents per gallon in exchange for worse fuel economy, and risk of damage to a very expensive engine. This is a Mercedes , not a Chevy. Let's really go crazy and assume 25,000 miles per year at 20 mpg = 1250 gallons per year. Take that times .20 cents and you arrive at the princely sum of $250.00. Mid-grade saves you $125 per year!

When I read the words, "It runs fine", I want to ask, "Really, when was the last time you took the heads off to look?"

Steve - I follow the manufacturer's specifications for fuel and other fluids.

Mid grade works fine in my '91 420SEL, I can use regular in the '88 420SEL with no appreciable difference. No knocking in either, ever.

There was a difference in mpg when "winter" blended fuels were used. Thank God! they've done away with THAT boondoggle!

"We are going to SAVE the WORLD by forcing you to use gasoline that results in worse gas mileage! Please pass the MBTE!"

Cheers!

(Well, except in "Nannyville", otherwise known as "The City that Works!", aka Portland, Oregon, aka "Sodom on the Willamette")

Thanks for the responses folks. I did pick up the 300SE from a fellow forum member. A great person who cares about cars makes the buying alot easier. Even better, the car is fantastic.

Im gonna go with the high octane and see how she runs. Mid grade is only 5-7 cents cheaper.

Anyway, just got the tags on it so she is on the road. I had a 123 but this is truly a different car. The big 6 is smooth as silk. Black on black. Looks great.