Regular Unleaded Gas Users Post here
Member
Joined: Mar 2006
Posts: 88
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From: Vancouver, BC
1997 E320
I cant imagine running 87 to save cents.. for crying out loud... not to mention the potential warranty issues with using 87.
MBWorld Fanatic!
Joined: Feb 2004
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From: SEATTLE WASHINGTON USA
'08 C300 Lux Barolo Red Beige Leather P2 MM 18" wheels '84 944
Bent valves?
<<This guy bought a new C class and ran regular in it, always insisting it was no different. Eventually he started getting some noise from the valve train so he brought it in to the dealer (still under warranty). They inspected the car and it turns out he bent a couple valves......>>
Pre-ignition is not going to bend valves. Piston and valve collisions bend valves and since the engine cannot be over-revved I don't see that happening.
Nice little anecdote, though.
Pre-ignition is not going to bend valves. Piston and valve collisions bend valves and since the engine cannot be over-revved I don't see that happening.
Nice little anecdote, though.
Newbie
Joined: Feb 2008
Posts: 13
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C300 Sport
I think it's safe to say that all engines produced today have knock sensors in them. However, we have no way of knowing exaclty how the knock sensor is configured to work. e.g., what is the low and high thresholds for engine timing? Since the C is a flex fuel vehicle, we know the knock sensor has the ability speed engine timing for 100 octane fuel. But how slow can it actually retard the timing?
Too much hassle for me to figure out, i'll just go with 93.
Too much hassle for me to figure out, i'll just go with 93.
You know this how?
Mercedes has no incentive whatsoever to make you use higher octane than you need, and of course Mercedes knows more about its "knock sensor" than do you.
I would suggest those proud of themselves for "beating the system" by using regular fuel put their money where their mouths are and post their VIN numbers here--cars to avoid on the used market for sure.
Mercedes has no incentive whatsoever to make you use higher octane than you need, and of course Mercedes knows more about its "knock sensor" than do you.
I would suggest those proud of themselves for "beating the system" by using regular fuel put their money where their mouths are and post their VIN numbers here--cars to avoid on the used market for sure.
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Joined: Oct 2007
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2006 BMW 323i
To the original poster....
The economics of the choice to run Regular Fuel don't work out with these cars. Mercedes runs knock-sensors which will retard the timing when you fill with Regular fuel.
Retarding the ignition timing avoids engine knock with fuel that has a lower octane number but has the side effect of a less efficient burn. This means that you make less horsepower AND you have worse fuel economy.
If you calculate the price you spend at the pump for premium and compare to the lower price of regular and take into consideration the worse fuel mileage you get on regular, you actually spend no more money on premium fuel than you do on regular. That's right, you pretty well break even and in some cases even finish ahead economically on Premium fuel. And, you get the added bonus of better quality fuel with premium, a better running engine, and a better detergent package to keep everything clean.
Face it... running Regular gas in these cars a losing battle.
The economics of the choice to run Regular Fuel don't work out with these cars. Mercedes runs knock-sensors which will retard the timing when you fill with Regular fuel.
Retarding the ignition timing avoids engine knock with fuel that has a lower octane number but has the side effect of a less efficient burn. This means that you make less horsepower AND you have worse fuel economy.
If you calculate the price you spend at the pump for premium and compare to the lower price of regular and take into consideration the worse fuel mileage you get on regular, you actually spend no more money on premium fuel than you do on regular. That's right, you pretty well break even and in some cases even finish ahead economically on Premium fuel. And, you get the added bonus of better quality fuel with premium, a better running engine, and a better detergent package to keep everything clean.
Face it... running Regular gas in these cars a losing battle.
Thread Starter
Member
Joined: Feb 2008
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2019 GLC 300
OK, OK...I get it
To the original poster....
The economics of the choice to run Regular Fuel don't work out with these cars. Mercedes runs knock-sensors which will retard the timing when you fill with Regular fuel.
Retarding the ignition timing avoids engine knock with fuel that has a lower octane number but has the side effect of a less efficient burn. This means that you make less horsepower AND you have worse fuel economy.
If you calculate the price you spend at the pump for premium and compare to the lower price of regular and take into consideration the worse fuel mileage you get on regular, you actually spend no more money on premium fuel than you do on regular. That's right, you pretty well break even and in some cases even finish ahead economically on Premium fuel. And, you get the added bonus of better quality fuel with premium, a better running engine, and a better detergent package to keep everything clean.
Face it... running Regular gas in these cars a losing battle.
The economics of the choice to run Regular Fuel don't work out with these cars. Mercedes runs knock-sensors which will retard the timing when you fill with Regular fuel.
Retarding the ignition timing avoids engine knock with fuel that has a lower octane number but has the side effect of a less efficient burn. This means that you make less horsepower AND you have worse fuel economy.
If you calculate the price you spend at the pump for premium and compare to the lower price of regular and take into consideration the worse fuel mileage you get on regular, you actually spend no more money on premium fuel than you do on regular. That's right, you pretty well break even and in some cases even finish ahead economically on Premium fuel. And, you get the added bonus of better quality fuel with premium, a better running engine, and a better detergent package to keep everything clean.
Face it... running Regular gas in these cars a losing battle.
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Member
Joined: Oct 2007
Posts: 148
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From: Rancho Cucamonga, CA
gets me from point A-B
I always use regular (87) in my R350 and i haven't had any problems so far. I have 4000 miles on it. No knocking, don't notice a lack in performance, I had it serviced once, and dealer couldn't tell.
Member
Joined: Oct 2005
Posts: 92
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From: Colorado
08 E320 Bluetec
UGGHHHH . . . I'm supposed to be the "frugal one" and I wouldn't use regular if premium were called for. If we can't get through to you, at least use PLUS!!
Those links to the articles you posted don't really help your case. The first one talked about not going OVER the recommended octane which is accurate. Some people think the higher octane will yield more performance. That's not true. Think of octane as a "burn rate timing agent." The higher the octane, the slower the fuel burns. If the car were designed for 87, you're wasting your money on anything higher because it's burning too slow for the power stroke itself. Your engine timing will be off the OTHER way = still bad!
The second article seemed to back you up a little bit but the "it seems okay now" stuff is going to get you in trouble "later." You need to have a little faith in the engineers and follow their recommendations. They gain nothing by making you spend more money on gas.
Also, the more expensive gas itself gets, the better bargain premium gets because it is ALWAYS a constant 20 cents a gallon more than regular!
If you're not going to listen to us and use premium, like I said above, at least use plus! Most manufacturers will err on the side of safety but going TWO grades below their recommendations is foolish.
Those links to the articles you posted don't really help your case. The first one talked about not going OVER the recommended octane which is accurate. Some people think the higher octane will yield more performance. That's not true. Think of octane as a "burn rate timing agent." The higher the octane, the slower the fuel burns. If the car were designed for 87, you're wasting your money on anything higher because it's burning too slow for the power stroke itself. Your engine timing will be off the OTHER way = still bad!
The second article seemed to back you up a little bit but the "it seems okay now" stuff is going to get you in trouble "later." You need to have a little faith in the engineers and follow their recommendations. They gain nothing by making you spend more money on gas.
Also, the more expensive gas itself gets, the better bargain premium gets because it is ALWAYS a constant 20 cents a gallon more than regular!
If you're not going to listen to us and use premium, like I said above, at least use plus! Most manufacturers will err on the side of safety but going TWO grades below their recommendations is foolish.
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The car will retard the timing and probably enrich the mixture in order to prevent knocking. You usually can't feel the carbon buildup until it is too late, although the dealer will be able to see preignition codes stored or active on the ecu. Just because you brought it in for service does not mean those things were checked.
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Sadly, plus will not cut it with these cars. They are programmed to have RON 95 (European octane rating, about equal to US 91-92) MINIMUM. The owner's manual, from what I remember does not reccomend 91, it only states that as the minimum in US (R+N)/2 rating. In Germany, octane grades below 95 are being phased out since there is no need for them.
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C300 Sport/Palladium Silver on Black/P2
With the price of gasoline today, 20 cents is a tiny percentage increase from regular to premium. I say why make the car perform and work differently than intended?
Member
Joined: Nov 2006
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From: MIRAMAR,florida
I have the 2008 C 350 sport. Irridium Silver Metalic,Multimedia Package,iPod,18" AMG wheels
dudedont use regular in your new car
No real affect that would "ruin" the car. But you are going to ruin the longevity of the car. Also you are not going to get the potential tourqe... Im shur that more members will add to the list of why you really dont wanna do this
, but in the meen time Welcome to MBworld.
-Mike
, but in the meen time Welcome to MBworld.-Mike
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From: Toronto, ONT
2008 C300
oh, we use Regular Unleaded with our C class in Hong Kong. The Regular in HK is already 100 Octane even on the fuel door it says Octane 100 is need in our HK C Class...the Gold one is like 110....
Last edited by newtonlaw; Apr 11, 2008 at 03:00 PM.
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What rating system is used in HK? I would imagine it to be different from the RON (EU) or (R+M)/2 (US) methods.
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C300 Sport/Palladium Silver on Black/P2
Yep, I bet that rating means something else in Hong Kong. However, if the fuel filler cap area says 100 and they are buying 100, I would suspect it's ok?
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From: California
2014 C250 sport
Try driving with the windows down, and listening to the engine under load. Youll hear crazy amounts of PINGING!! The C-class loaners we get from the dealer(owned by Enterprise rent a car) obviously get regular 87 octane put into them, and they ping like MAD. I dont care what anyone says about the engine management compensating, because it doesnt do a very good job at all. Heck, even with 91 octane I can hear, once in a while, some light pinging in our cars because of the high compression. Put Premium to save the engine from the excessive pinging!
