maybe a stupid question..but why not - PeachParts Mercedes-Benz Forum

JamesDean · #1 08-24-2006, 10:35 AM

I know the manual for my 190 2.6 says to put in atleast 91 octane fuel...someone asked me why not put in 87 octane and use an octane booster like something one can buy from the autozone..?

i've been putting in 93 octane fuel...its been hovering around 2.97-3.01 where I get it versus 3.29 everywhere else..so i'm not really complaining

just a thought.

kris

Ron in SC · #2 08-24-2006, 10:48 AM

Quote:

someone asked me why not put in 87 octane and use an octane booster like something one can buy from the autozone..?

I've alway heard they are useless.

lee polowczuk · #3 08-24-2006, 11:11 AM

we run mid grade in ours with absolutely no problem

when it is really hot , i might put in premium...

i put in a can of bg44k once a year...may techron once in between.

Ferdman · #4 08-24-2006, 11:45 AM

Kris, follow the adage "Pay me now, or pay me later". Realize that the automotive engineers establish fuel requirements for a reason. It's best to follow fuel requiements noted in the Owner's Manual. The cumulative effects of using a lower octane gas may very well result in reduced engine life or an expensive repair bill down the line. Then what have you saved by using a cheaper grade gas?

gmercoleza · #5 08-24-2006, 12:11 PM

93 Octane is just a precaution in the M103 without a knock sensor. I have found that, in most cases 89 octane works fine. As the summer temps here in TX approach 100+ then I will occasionally hear slight pinging under moderate load in high gear on the highway. Then I know it is time to bump up to 93 for the remainder of the summer. As we move into winter with consistently lower temp weather, I switch to 87 octane which I continue to run with NO PINGING until the weather starts to warm up and the cycle starts all over again.

With regard to octane boosters, they do in fact work, but read the bottle carefully. One bottle is only good for a few gallons and you will find that you need 2 to 3 bottles to treat a full tank. After adding in the cost of the bottles, I'm sure you will easily surpass the cost of just going with premium fuel. Around here, the difference is only about 10 cents between grades. That's only about 3% when dealing with fuel prices hovering around $3/gallon.

manny · #6 08-24-2006, 12:41 PM

As stated above, using octane booster is false economics.

Last time I read a reliable test, it was determined that they are GROSSLY over-rated.
Instead of boosting the octane the claimed 2,3,4, or 5 points, all of them, in real world testing, hardly achieved half of the claimed numbers.
Buy the real stuff ( best gasoline ) at the pumps.

JamesDean · #7 08-24-2006, 01:39 PM

i thought as much about these products...either they didnt work at all or it would take more money for them to work because one would need to by in quantity which would surpass the money spend on the actual fuel....after reading an article on different acclaimed octane boost products, i'm convinced that it would be a waste of money to attemp to "upgrade" a lower octane fuel to the necessary level. $10-25 for a bottle that teats x gallon..maybe one will get two uses out of that..thats an addional $5 (minimum) per tank of fuel vs. an additional $3 per tank for the actual 93 octane fuel...

i've never heard pinging before...my fuel economy in the 190E is roughly 20mpg. I've still not gotten used to the fact that the tank is only 14.5 gallons. Seeing it sit near 1/2 tank and seeing near 125 miles since full got me worried. I'm so used to the w126's 23.3G tank.

Heres a question: on the fuel gauge there is markings for Full, 3/4, 1/2,1/4 and R...when the needle is on 3/4 does it mean there is 3.2 gallons or 3.6? Does the fuel gauge read the full 14.5G or does it read the 12.9 (everything but the reserve)?

gmercoleza,
how many years have you been going with that cycle..it gets pretty cold up here in the winter.

Ferdman,
the manual says a min. of 91 octane. Around here its 87,89,93. I havent seen any 91 in a long time and if I have its most likely going to be more expensive than the 93. I buy my fuel at a competitive truck stop area so fuel is always cheaper than the stations around town. when RUG was 2.85 at the corner station it was 2.65 at the truck stop.

lee polowczuk,
i thought about running a bottle of Techron through but was unsure if it would be worth it...I think its about $12/bottle for 20gallon and $9 for 12...

whats this BG44k do?

Thanks everyone,

Kris

lee polowczuk · #8 08-24-2006, 01:45 PM

techron and bg44k are fuel injection cleaners...

i didn't mean to imply that i was doing it for octane reasons...

i just think keeping my gas burning efficiently helps when i am using mid-grade..

bg44k is widely accepted as being the best system cleaner. of course it's pricey...

gmercoleza · #9 08-24-2006, 02:08 PM

Quote:

Originally Posted by JamesDean

gmercoleza,
how many years have you been going with that cycle..it gets pretty cold up here in the winter.

Have only been in TX for 2 years, and only started going with higher grades gas once we got here. Back home in Chicago I ran 87 year round in all my MBZs, never heard pinging until I got down here. I think 95 degree Chicago summers are more brutal because of the high humidity, but realistically down here in TX it's not uncommon to go well above 100. That's when I start hearing pinging and at that point I will always run 93 as insurance. The heat really has a lot to do with it.

JamesDean · #10 08-24-2006, 03:29 PM

f im not mistaken there was a year when MB recommended 87 for the m103 then changed the engine a little and recommended 91....

also there is a resistor that retards the timing to compendate for cheap fuel...mine is absent. Normal (US) is a 6 degree retard. Europe has an adjustible resistor..while US model have a fixed one...I dont know what this will play in running mid-grade 89 or lower 87 grade fuel).

EricSilver · #11 08-26-2006, 07:17 PM

Right now (in Virginia) Sunoco 93 is a relative bargain -- only a 2-cent price difference between it and 91 octane, versus the 10+ cent difference between 87 and 89, and 89 and 91. So it is advantageous to go with the highest octane.

Also, it appears gas prices have begun dropping in the last week or two. I wonder how far they will fall by Election Day....

JamesDean · #12 08-26-2006, 08:31 PM

yes the gas station I go to (last price) was 2.97 for premium vs. 2.75(?) for regular.

If i were to purchase 9.557G (last fill up):

Regular: $26.28
Premium: $28.38

a total of $2.10 difference!

When you see the different prices one usually thinks "wow premium is soo expensive" when in actuality its only a few mere dollars more...$2.10 one can probably find in one's ashtray.

I'll stick with my premium 93. The 190 2.6 gets pretty decent fuel economy 20-22 city / 32 highway.

That 22mpg is accurate too. Usually I have a tendecy to play with the numbers to make myself feel better about the mpg..

but this was true and I was actually impressed.

Moral of the story: Chock up the chump change for the premium. Its not all that much more expensive.

Kris

Hit Man X · #13 08-27-2006, 12:56 AM

You could always buy Toulene or Xylene in a 55 gal drum, figure out the mix ratios to achieve 92-94 oct from your 87 with the Toulene or Xylene added.

But I agree, just run 91+ as cost difference isn't there.

Joe Bauers · #14 08-27-2006, 11:05 AM

Actually, an MB tech recommended the mid-range for my 103 engine some time ago. He said that the onboard computer would adjust with these engines, and that 87 octane would work just fine as well. He simply preferred the mid-range, 89, octane. He also said that in the early days of the 103s, whenever they would run into a rough idle problem or a performance problem that they could not figure out, the MB rep recommended running the lower octane fuel because, for some reason, they ran better on it.

Joe B.

davestlouis · #15 08-27-2006, 11:46 AM

I run 93 octane in my 420SEL...I've tried midgrade but I swear I feel a lumpy idle with cheaper gas. In the midwest there is 10% ethanol in all the gas we can buy, I wonder if that has anything to do with running issues?