What kind of gas do you use?
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Joined: Nov 2007
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From: Phoenix, AZ
2014 Ghibli S Q4 & 2008 C350
I plan on continuing using 91 which is about the highest they sell here in MN. While I've never been able to tell the difference while driving in a car, I could sure tell the difference which gas I put in my motorcycle back in the day. (Which was a Wednesday in case you didn't know that 
- DC) The cheap 87 oct was ok, 91 better, but 100+ racing fuel, which they wouldn't let me pump directly in to my bike, would make it scream.
- DC) The cheap 87 oct was ok, 91 better, but 100+ racing fuel, which they wouldn't let me pump directly in to my bike, would make it scream.
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Joined: Feb 2004
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From: SEATTLE WASHINGTON USA
'08 C300 Lux Barolo Red Beige Leather P2 MM 18" wheels '84 944
Flex fuel?
C300 is, C350 isn't. C300 has plastic fuel tanks, and many differences for E85 including the ability to sense a changeover to E85.
I don't know why anybody would want to use E85 anyway. If you want to save the world, buy a Prius.
I don't know why anybody would want to use E85 anyway. If you want to save the world, buy a Prius.
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Joined: Feb 2004
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From: SEATTLE WASHINGTON USA
'08 C300 Lux Barolo Red Beige Leather P2 MM 18" wheels '84 944
E85 vs E10
<<Some areas you can't help it though...in the Northeast, all gas stations have up to 10% ethanol added to gasoline.>>
Which is E10 and has no effect except a 10% drop in fuel mileage. And has nothing to do with the E85 question.
Which is E10 and has no effect except a 10% drop in fuel mileage. And has nothing to do with the E85 question.
Member
Joined: Aug 2007
Posts: 198
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From: Seattle, WA and Portland, OR
2008 C350 and 2003 Z4 3.0
The actual science behind octane is just that the higher the octane rating, the lower the temperature at which it combusts. (that a real word? 
) Lower octane ratings mean that the cylinder wall temp will be higher, which can lead to "knock", aka pre-detonation. This is when fuel combusts before it is supposed to due to the higher temps in the cylinder. No biggee because all engines since spandex went out of style have knock sensors (don't know when exactly, but it's been a long time) that will dial back the ignition timing to prevent the knock.
So while it's perfectly safe to do so, running a lower octane than the engine was designed for probably isn't netting you the best performance if the timing gets dialed way back. My personal experience has been that if the motor is "high strung" (has a high-ish compression ratio) running lower octane gas usually results in a some nasty pinging and knocking on big hills when you stomp the gas. Most times though, if you had the stereo on you'd never know the difference.
Really depends on your tolerance for such things, and how much you feel like you're saving.
) Lower octane ratings mean that the cylinder wall temp will be higher, which can lead to "knock", aka pre-detonation. This is when fuel combusts before it is supposed to due to the higher temps in the cylinder. No biggee because all engines since spandex went out of style have knock sensors (don't know when exactly, but it's been a long time) that will dial back the ignition timing to prevent the knock.So while it's perfectly safe to do so, running a lower octane than the engine was designed for probably isn't netting you the best performance if the timing gets dialed way back. My personal experience has been that if the motor is "high strung" (has a high-ish compression ratio) running lower octane gas usually results in a some nasty pinging and knocking on big hills when you stomp the gas. Most times though, if you had the stereo on you'd never know the difference.
Really depends on your tolerance for such things, and how much you feel like you're saving.
I use 92 in my C350.
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From: SEATTLE WASHINGTON USA
'08 C300 Lux Barolo Red Beige Leather P2 MM 18" wheels '84 944
Knock sensors
<<No biggee because all engines since spandex went out of style have knock sensors (don't know when exactly, but it's been a long time) >>
My 1984 Porsche has a Motronic engine management system but does not have knock sensors which came in 1986. No MB without such a system has sensors and in fact the M104 engine was the first C engine ('94) to have a Motronic system. When the sensor detects detonation (before you hear it) it retards the timing and after a short period (milliseconds, I've heard) advances it until it hears pinging again.
The consequences of detonation at high power settings are melted pistons and a hole in your wallet, simultaneously.
Our W204s have the very latest knock detection so we are OK. Still, I'm buying premium.
My 1984 Porsche has a Motronic engine management system but does not have knock sensors which came in 1986. No MB without such a system has sensors and in fact the M104 engine was the first C engine ('94) to have a Motronic system. When the sensor detects detonation (before you hear it) it retards the timing and after a short period (milliseconds, I've heard) advances it until it hears pinging again.
The consequences of detonation at high power settings are melted pistons and a hole in your wallet, simultaneously.
Our W204s have the very latest knock detection so we are OK. Still, I'm buying premium.
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Joined: Oct 2007
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From: Northern NJ
C3004Matic Sport, Blk on Blk, Pano, P1, MMC, Ipod
I use bills.
I've decided to cut out the middleman, I just shove wads of cash down the filler pipe. usually 5's and 10's, 20's when its low, and the occasional 50 or 100 when I want to impress people. 
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Member
Joined: Nov 2007
Posts: 87
Likes: 2
From: Toronto
C300 Sport
I had a new 2003 Nissan Murano. I lived in Oregon where only the gas attendant can fill up your car. For the first year that I owned it I put regular in, then on a visit to Seattle, WA I stopped and put gas in myself. When I opened the filler door there was a sticker that said use 91 Oct. I started to use the higher oct and never noticed any difference.
I use 92 in my C350.
I use 92 in my C350.
New C "requires" 91 octane.
Simply put, most modern imports engines have high compression ratio. Low octane gas will detonate while the piston is going down, IF you push the engine. If you drive like a 80 yr old granny, low octane gas can not harm your engine. But if you ever do rev it, thn it'll cause problem. Piston is trying to go down, and explosion is trying to push it up = very bad. Manual clearly states that you may use low octane gas in emergency, but you need to drive very slowly.
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From: New Jersey
E550 4MATIC
Just to add to the discussion...
I was filling up my car the other night and noticed that the car in front of me, a Range Rover HSE had the regular hose hooked up. This pissed me off...the jerk spent $80K on a stupid guzzling SUV and then doesn't want to spend the extra 15 cents to put premium that it NEEDS.
The gas station guy noticed me shaking my head (yes I live in NJ where we don't pump our own gas but I usually get out anyway and wait), and I said I can't believe how cheap people are. He said seriously the majority of people buying high end luxury cars around here put regular in. I guess considering the high lease rates in the northeast maybe the idiots feel like it's not their problem and they don't care. Really sad imo.
I was filling up my car the other night and noticed that the car in front of me, a Range Rover HSE had the regular hose hooked up. This pissed me off...the jerk spent $80K on a stupid guzzling SUV and then doesn't want to spend the extra 15 cents to put premium that it NEEDS.
The gas station guy noticed me shaking my head (yes I live in NJ where we don't pump our own gas but I usually get out anyway and wait), and I said I can't believe how cheap people are. He said seriously the majority of people buying high end luxury cars around here put regular in. I guess considering the high lease rates in the northeast maybe the idiots feel like it's not their problem and they don't care. Really sad imo.
Member
Joined: Oct 2007
Posts: 118
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From: Toronto CANADA
08 C350 4Matic -Premium- Comand NAV-Keyless-GO-Panoramic-Rear Win Sunshade-Memory seat-Quickpark-AMG
use 91 , but i saw 1 guy put 87 on his C300 last week , he said....same thing....can move will no problem what kind u use!!
Member
Joined: Nov 2007
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From: outside chicago
2008 c300 luxury, P2, MM, Capri Blue Metallic
well, here in chicago land, I can get E85 for about $2.50 per gallon, and since its 100+ Octane, the car drives like a bat out of hell!
The only down side to E 85 is that your mileage suffers by about 20%, but since I am saving over 30% in gas prices, ($3.50 for Premium, VS $2.50 for E 85), its an easy decision for me..
Benz doesnt recommend using it when temps are below 14 degrees F, so I will stop using it here in a week or 2 when the temps go close to zero for a couple of months, but definately during the rest of the year, we will be using it..Car runs great on it, so you should try a tank!
Just remember to let your tank run down to 1/3 full or less, and shut off the car when re-fueling..that way, when you turn it back on, the computer senses the E85, and adjusts the engine accordingly..
The only down side to E 85 is that your mileage suffers by about 20%, but since I am saving over 30% in gas prices, ($3.50 for Premium, VS $2.50 for E 85), its an easy decision for me..
Benz doesnt recommend using it when temps are below 14 degrees F, so I will stop using it here in a week or 2 when the temps go close to zero for a couple of months, but definately during the rest of the year, we will be using it..Car runs great on it, so you should try a tank!
Just remember to let your tank run down to 1/3 full or less, and shut off the car when re-fueling..that way, when you turn it back on, the computer senses the E85, and adjusts the engine accordingly..
