"Car runs okay." WTF does that mean? I doubt those were their words.

Going from premuim to mid-grade makes little sense. Look at the octane drop and the price difference between premium to mid-grade and premium to regular.

This discussion is inane.

 

I did not see that motor week but if you are talking about Pat Goss or Gloss whatever his last name is. He would use the words "Car runs okay." That show started in Maryland and my dad and i used to watch it all the time when it was only on Maryland Public Television. Over time we have agreed and disagreed with what he has to say. He is just a car mechainic that owned his own shop and ended up on tv.

 

The other point is more important.

And, it's Goss.

 

I speak from my own experience, my 1996 C220 with 154K miles sets the CEL for knock sensor 100% of the time if I run on anything less than 91, and often will on 91. The CEL code is set for knock sensor, and will not reset itself either without unhooking the battery or using my ODBII code reader/resetter - I bought one of those nifty devices just for my MB's a long time ago since they like the orange color so much I think. I think it might reset itself after 60 restarts or so they say, but I don't like the orange light in my face. In Arkansas we have 93 as the premium and thats what I have to use to prevent having to reset the CEL every few days. If I run regular, which is 86 here, it will set the CEL before I get half way home up the mountain. I have mixed 91 into 93 a few times if I am away from home where they have no 93, but for a couple bucks it isn't worth it to me to cheap out and have the trouble. Your C220 will more than make up for that dollar or two by the 30+ mpg it gets on premium. I have gotten 36 mpg before if I drive 55 on rural highways with no stops, but always get 30 mpg at 85 mph on the interstate even with the a/c on.

 

Euro car engines are built a bit different then most other country's. <MB, BMW, SAAB, even french and english cars are timed in such a manner as to take advantage of high octane gasoline. Also, if you keep up with American cars, most of the big cars require 91 octane also, only the econo boxes don't. Also, a good brand of 91 will keep your engine running better for the long haul. I drive 65 to 70mph on the highway and have a medium heavy foot and get 27mpg on my 99 C280 and I mostly use 93 Shell. Around town I get 19 to 21 mpg.

 

I can't say that premium fuel will make your car BETTER but I can vouch that it won't make it WORSE. I have owned a BMW 323i where I put 100,000 miles on with all 87 octane gas. No problems at all. I currently have a C240 where I have 70,000+ miles also on 87 gas. I think the oil type is a much more important factor in the longevity and performance of the vehicle. Pinging should not be an issue as the ECU corrects this and let's face it, the C-class Mercedes is not a high-performance engine, with the exception of the AMG model.

I find it amusing how some folks claim the "cheapness" defense if you don't put in premium (Well why buy a LUXURY car if you don't buy PREMIUM gas?). Yet it's some of these same individuals (no one on here but I do know plenty) who put on mediocre tires and shoddy aftermarket parts which are much worse for the car than unleaded pump gas.

 

My understanding is that all M-Bs, like all performance cars, use graduated ignition timing tables that take advantage of premium grade gas. If you use premium, the timing is advanced for maximum performance. It doesn't add performance, which is a common misconception, but it allows the engine to perform at its maximum designed performance. If you use regular (87 octane) the timing is retarded to prevent pinging. Unfortunately, retarding the timing also retards performance. To each his own, I guess.

 

This debate can go on forever. I use what the manufacture recomends 91+ in the Benz good ole 87 in the Isuzu. Simple as that. And if somebody doesn't want to pay for any more than the cheapest gas then dont buy a car that requires it. I dont care if u buy ur car new or used.

 

why not just do what the directions say?

If it says use synthetic oil then use synthetic oil.

If it says use premium fuel then use premuim fuel. Is it really that hard to understand.

yes your car will run with lower octanes, but it wasent designed to!

 

In the UK reguler gas in a 95 RON Octane number, premium is 98.

Personally, I always buy 95. Maybe I'll try 98 someday.