Gas

[SmartKing]

Its recommended that you use 91 or 95 high octane. Will it hurt anything to use the lower octane like 87 or 85?

[spdickey]

Originally Posted by SmartKing

Its recommended that you use 91 or 95 high octane. Will it hurt anything to use the lower octane like 87 or 85?

Quick answer to you question is, no.
You will find numerous discussions on this topic. Search is your friend.

[SmartKing]

Ok, cool. thanks.

[randyzimmer]

Winding Road - October 2008

page 71

[Old smart]

Originally Posted by SmartKing

Its recommended that you use 91 or 95 high octane. Will it hurt anything to use the lower octane like 87 or 85?

When you read "95" on the inside of gas cap door, it is "95 RON" (Research Octane Number). The "91" is U.S. PON (Pump Octane Number, or Anti-Knock Index). To convert RON to PON/AKI, multiply RON by 0.95.

[Dave Van]

Yea...we talked this one a bunch....I say for $1.60 per tank....it is well worth it...My pure gets 46-49+ mpg on prem....why save $1.60 and risk warranty claims etc?

[fortow]

Originally Posted by Old smart

When you read "95" on the inside of gas cap door, it is "95 RON" (Research Octane Number). The "91" is U.S. PON (Pump Octane Number, or Anti-Knock Index). To convert RON to PON/AKI, multiply RON by 0.95.

I guess that's one way of doing it - I always use the formula MON+RON/2 to get pump octane. The recommendation is 85 MON, 95 RON - so the recommended minimum pump octane should be at least 90.

If lower octane is used power is reduced as well as fuel mileage. Higher octane doesn't give an engine more power, it just reduces the liklihood of detonation if the engine is timed properly. Using lower octane forces the ECU to retard ignition and that results in less power and a less efficient engine reducing mileage as well.

[Cruising n Coasting]

Originally Posted by Dave Van

Yea...we talked this one a bunch....I say for $1.60 per tank....it is well worth it...My pure gets 46-49+ mpg on prem....why save $1.60 and risk warranty claims etc?

Same goes for driving an extra 5 miles to save 3 cents a gallon, that's only 20 cents minus the gas wasted to get there and back.

[SylenThunder]

I have been playing around with it... and have used 87 octane in the last two tanks. The first thing that I noticed was a huge drop in the performance. The second thing that I noticed, is that because of this drop, I have been using a lot more pressure on the accelerator to keep it going. I do a lot of highway driving and it would probably be okay for someone with a lot of city driving, but my mpg went from 38-41 with 93 octane down to 32-35 with 87 octane. Considering that there's only $0.20 difference between the two octanes... I'll be switching back to 93 on the next tank.

Also, after the first tank of 87, I have noticed a bit of a knock from the engine... It's fairly quiet, but worrisome.

[Old smart]

I will use 91+, as it is false economy to do otherwise. But whereas I buy gas on the various local military bases (we got'em all, selling NAVgas, ARgas, CORPSgas, AIRgas, GUARDgas), and none of it is "Top Tier," I will be using an anti-fouling additive as noted in the N.A. smart Owners Manual (pg. 307). I'm not sure yet what the official smart recommended list is, but I have heard that M-B recommends "Techron," as used in Chevron/Texaco top tier fuels. Shell's top tier additive is "V-Power" and blended in their premium gas (only). Conoco/Phillips/76 uses "PROclean," but I don't know if it is available separately as Techron and V-Power are. There are likely others from non-gas companies.

Top Tier Gasoline