Fuel requirements
Thread Starter
Joined: Feb 2004
Posts: 87
From: South Carolina United States
Fuel requirements
My 89 300SE shows that I should use 93 octane fuel but with the prices climbing almost daily, would there be any detrimental effects if I at least backed down to 89 octane?
Joined: Dec 2003
Posts: 3,766
From: Georgia, USA
RE: Fuel requirements
If you hear any pre-detonation (pinging) go back to the higher octane.
It will probably take a tank or two or three, depending on your fill-up routine, to get to a full tank of pure 89 octane. When you think it's there, go for a test drive. Press the gas pedal all the way down slowly while going up a hill. If it pings, go back to the higher octane to prevent engine damage.
It will probably take a tank or two or three, depending on your fill-up routine, to get to a full tank of pure 89 octane. When you think it's there, go for a test drive. Press the gas pedal all the way down slowly while going up a hill. If it pings, go back to the higher octane to prevent engine damage.
Joined: Feb 2004
Posts: 59
From: United States
RE: Fuel requirements
unless your going to change the timing and loose HP, your in big trouble running low grade gas. Think about two hammers hitting one and other when the spark plug fires. Unless Sleepwalker knows how to adjust don't run grapyyyy gas. Or better sell your car and buy a Ford Taurus... remember this is a highend car that will go 300,000 plus if taken care of correctly. Don't mean to sound like the father of Mercedes, but thats what it is. [>:]
Joined: Mar 2004
Posts: 49
From: Australia
RE: Fuel requirements
My 1980 500SE users manual says to use petrol with a minimum octane rating of 98. However I find it starts up faster if I use 91 Octane unleaded or 96 Octance Lead Replacement than with 98 octane unleaded and theres no noticable performance or running difference on any of them.
Joined: Jan 2004
Posts: 270
From: United States
RE: Fuel requirements
the higher the octane number, the better it is at preventing engine knock.
most cars are equipped with knock-sensor, the computer will know when a low-grade fuel is added and "adjust" itself to comply with the low-grade fuel.
the knock-sensor is installed as a safety device, not a money-saving device.
most cars are equipped with knock-sensor, the computer will know when a low-grade fuel is added and "adjust" itself to comply with the low-grade fuel.
the knock-sensor is installed as a safety device, not a money-saving device.
Joined: Dec 2003
Posts: 3,766
From: Georgia, USA
RE: Fuel requirements
One other thing. I don't think the mid-grade fuels are a good value. Look at the difference in prices and octane ratings between the:
mid-grade versus high-grade
compare it to the differences between the:
low-grade versus mid-grade.
If you pay for the mid-grade, you may as well pay for the high-grade. It's not that much more but the octane rating is.
Also, take the foreigners' info with a grain of salt. Their countries don't have the same emissions requirements as the USA. For example, look at Flyingphils post where he's talking about 98 octane gas at the pumps. When's the last time you saw that? Engines can be "tuned up" when you have good gas like that. If it's tuned for 98 octane gas, it's going to ping like crazy with 89 octane.
mid-grade versus high-grade
compare it to the differences between the:
low-grade versus mid-grade.
If you pay for the mid-grade, you may as well pay for the high-grade. It's not that much more but the octane rating is.
Also, take the foreigners' info with a grain of salt. Their countries don't have the same emissions requirements as the USA. For example, look at Flyingphils post where he's talking about 98 octane gas at the pumps. When's the last time you saw that? Engines can be "tuned up" when you have good gas like that. If it's tuned for 98 octane gas, it's going to ping like crazy with 89 octane.
Joined: Jan 2004
Posts: 270
From: United States
RE: Fuel requirements
ORIGINAL: Lugnut
One other thing. I don't think the mid-grade fuels are a good value. Look at the difference in prices and octane ratings between the:
mid-grade versus high-grade
compare it to the differences between the:
low-grade versus mid-grade.
If you pay for the mid-grade, you may as well pay for the high-grade. It's not that much more but the octane rating is.
Also, take the foreigners' info with a grain of salt. Their countries don't have the same emissions requirements as the USA. For example, look at Flyingphils post where he's talking about 98 octane gas at the pumps. When's the last time you saw that? Engines can be "tuned up" when you have good gas like that. If it's tuned for 98 octane gas, it's going to ping like crazy with 89 octane.
One other thing. I don't think the mid-grade fuels are a good value. Look at the difference in prices and octane ratings between the:
mid-grade versus high-grade
compare it to the differences between the:
low-grade versus mid-grade.
If you pay for the mid-grade, you may as well pay for the high-grade. It's not that much more but the octane rating is.
Also, take the foreigners' info with a grain of salt. Their countries don't have the same emissions requirements as the USA. For example, look at Flyingphils post where he's talking about 98 octane gas at the pumps. When's the last time you saw that? Engines can be "tuned up" when you have good gas like that. If it's tuned for 98 octane gas, it's going to ping like crazy with 89 octane.
I think Flyingphil was talking about 98 octane in Australia, not in U.S. (98 octane is sold in Taiwan also)
The octane number in U.S. are lower because the number we use is the average of RON (Research Octane Number) and MON (Motor Octane Number) ----- (RON+MON) / 2
But other countries only use "RON"
Like all Mercedes sold in the U.S. (current models) requires 91 octane, thus -- 96 RON + 86 MON / 2 = 91
I've read on Car and Driver and it said the AMG 65 bi-turbo engine requires octane 104 (RON)
