Doo doo or no, my car runs terrible on regular. It pings when under full load, is slow on the get go and runs a little rougher at idle. The 5 bucks extra per tank is worth it to me!
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While not worth it to me, a compromise is to buy 1/2 93 octane and 1/2 89 octane. This will give you 91 octane, which is what the manual calls for.
You know, that is not a bad idea.
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I just couldn't give up on my 1995 E320.
I think it might be like always going back to that same bad relationship with an ex girlfriend.
You feel you love them too much, or you are just too stupid to know any better.
Engine with high compression ratio requires high octane gas. I'm not sure if 300e's engine has high compression ratio.
BTW, Higher octane gas is not better than lower octane gas. It's just higher octane gas explodes in higher compression. My friend use 91 octane gas in his 91 Honda Civic which is completely waste of money. He insists his car runs better with 91 gas. Actually, what he need is a tune up and adjust the timing, etc.
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79 450 SLC
93 300E 2.8
93 Toyota MR2 T-top 5sp
06 BMW 325i (hers)
92 BMW 525i (sold)
Last week I was involved in an accident and totalled my 400E. But when I was driving my 400E I always used premium and never thought twice about the extra $4.00 everytime I filled up. What the heck, forget your latte for the day if it bothers you that much. On one occasion I was in the boonies of Alabama and stopped to filled up finding out that I had a choice between diesel and regular. I filled with regular and the car ran like garbage; missing, lack of power and guzzled the fuel. When down to 1/2 tank of fuel (not very long) I filled up with premium and noticed a difference within miles. As I recall it took another tank to get my mileage and performance back to where it should be. So for me, if you own a Mercedes you need to treat it like the quality vehicle that it indeed is. Don't scrimp on fuel.
but arent unburned hydrocarbons the result of poor ignition, rather than fuel?
Overly rich condition is not caused by ignition....
Either case, poor tune or too rich can cause the unburned portion to ignite in the cat, potentially causing damage.
How do I know?
We rattled the bricks loose on two brand new 5.0L Merc cats on the dyno, while setting the fuel maps for the twin turbos.
Perfect ignition, just a bit too rich for the stock cat.
Didn't have a problem after we installed a newer technology spun metal cat.....
the knock sensors are only available on the M104 engined 124s. the M103 engined ones do not have knock sensors.
if they detect pinging they pull the timing. so your whole the fuel burned my cat tripe is just that, tripe.
as stated already, the cats will get fried if you use leaded fuel.
if your cats are gone with unleaded then you have another unresolved problem that changing fuel octane might hide, but not eliminate.
Well, Let me say this about that. I am telling you what happen when I put regular in my 94 E320 which is a M104 engine and when timong retards to prevent detonation it leaves unburned gas behind which then tends to overheat the catalytic converters. I don't know how sensitive the Mercedes cats are to this but there have been problems in other cars when this condition happens. I think it is you who is posting Doo Doo, my friend.
Oh just to let the first post guy know. I didn't experience any problem with the catalytic converters as a result of this brief encounter with regular fuel. But then again I was very careful to drive it conservatively because I could tell it wasn't like the regular fuel. Whether or not extended use of regular will damage the cats used on these cars - I don't know and I don't want to find out. The first point I was trying to make was that the is no economy in using the regular gas because you lose the cost savings in less miles per gallon. I do like the cocktail (Mixture) idea that somebody else posted since these gas prices are going wild. If the car requires 91 then putting in 93 isn't giving you anymore. I guess you also do 2/3 of 93 octane and 1/3 of 87 octane - correct? Kind of hard to justify the extra hassle though, but gas prices being what they are - It is starting to look more attractive all the time.
Vehicle: W124 E320 Coupé 1996, W124 300E twin turbo 1990, W126 300 SE 1991, Ford Capri 2.8i 1984
Location: Harpenden, England
Posts: 98
The compression ratio is 10 in the M104 and 9.2 in the M103, but it's 8 in the low-compression M103 (.94, .981, .983, .985). Source: MB's Technical data passenger cars (Oct. 93).
Vehicle: 2003 C320 Coupe\71 220 gas, 4-speed\95 Talon TSi AWD\97 J30\79 GS1000S\80 SR500\'69 Datsun 2000
Location: glorious Galt CA
Posts: 83
Quote:
Originally Posted by Glide Ride
While not worth it to me, a compromise is to buy 1/2 93 octane and 1/2 89 octane. This will give you 91 octane, which is what the manual calls for.
Um... unfortunately, chemistry does not equal "math"; your concoction isn't yielding 91.
Unburned fuel will overheat a cataclysmic diverter. How much, over how long will "depend". What kills them is leaded gasoline: the lead coats the catalyst, and insulates it from operating. Often, reverting to unleaded will clean them back to functioning over time.
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