 » Site Navigation | | | | » Recent Threads | | | |  |  |  |  08-23-2005, 09:44 PM | #1 | | Junior Member Join Date: Feb 2004 Location: Mountain View Posts: 4 |  Is it ok to use 89 octane gas?
I have a 1996 318ti with 118L miles on it. I've been using 91 octane gas for it so far, as thats what the previous owner did.
With the price of gas touching $3/gal here (san francisco, CA: ouch!) I'm thinking of going down a notch: 89 octane.
I know it will hurt the car in _some_ way; but does anybody know specifically what? Engine wear? Milage? Less power? Has anyone tried it?
TIA,
Rommel |  |  | | 08-23-2005, 09:52 PM | #2 | | Senior Member Join Date: Aug 2004 Location: state college, pa Posts: 3,431 |
octane is a measure of knock, not of cleanliness.
i've seen no performance gains using 91 over 89, and in fact the car seems to run better on 89.
i only buy 91 when i'm running out of gas, and it's a shady station or if it's the day after they fill the tanks (stirs up sediment). in most cases, 89 will do you fine--or at least 80k of 145k miles on my ti tells me so. | | | | | 08-23-2005, 09:55 PM | #3 | | Senior Member Join Date: Jun 2005 Location: St. Louis Posts: 138 |
It should say the minimum AKI on a little sticker near the gas cap. __________________
97 sport | | | | | 08-23-2005, 10:02 PM | #4 | | aka Stabby Join Date: Nov 2004 Location: Mead, CO Posts: 5,336 |
i believe i've run 89 most of the 212k miles i've driven ... __________________ 1996 318ti, California package, 267k miles
current mods: bilstein sports, bavauto springs, e30 m3 LCABs, solid metal ball joints, bavauto RSMs w/reinforcements, e30 3.73 LSD & halfshafts, supersprint cat-back exhaust, turner rear sway bar reinforcements, IE poly subframe & RTABs + camber/toe kits, powdercoated e36 32x front calipers, sport mirrors, H&R 28mmF/19mmR sway bars, x-brace, auto solutions SSK w/poly bushing upgrade, BMW CD43 head unit, DICE HD Radio w/iPod integration and "stealth" HD antenna, staggered style 68s, orange electronic TPMS, leather arm rest, JT Designs metal undertray
acquired and awaiting install: heated seat kit, cali top switch relo, lumbar support kit, park distance control kit, heated washer nozzle kit, m-coupe rear subframe, trailing arms, differential, and halfshafts, m-coupe front/rear brakes with master cylinder, under hood light kit, mud flaps, rear sun blind, auto-dimming rear view mirror, tilt steering wheel retrofit, apexcone 5000K HIDs with 55W ballasts
2002 X5 4.4 Sport Package, 53.5k miles
Current Mods: e46 m3 steering wheel | | | | | 08-23-2005, 10:46 PM | #5 | | TRETEN IRGENDEINES ESELS Join Date: Aug 2004 Location: Rhode Island Posts: 3,687 |
I just use regular unleaded,in the winter i'll get super a couple times but thats about it. When i was in NH on saturday at the dragway you can buy 100+ octane there. __________________ 98 Avus Blue 318 ti Active
clear outs all around,stealth turning signals,blue led interior lights, 35% tinted windows,K&N air filter, 12" Kenwood Sub, MTX Thunder Amp,Alpine cd changer, Leatherz Armrest,ACS Pedals/Handbrake/FloorMats & Vitesse Tuning Carbon Fiber B-Pillars/CF Spark Plug Cover, New 16" MSW Typer 14 Rims on Goodyear Triple Treds 
www.myspace.com/avusblueti | | | | | 08-23-2005, 11:15 PM | #6 | | Senior Member Join Date: May 2005 Location: England, UK Posts: 1,288 |
$3 a gallon??!! ROFLMFAO!!!
its about 8-9 here. __________________
1995 BMW 316i Cosmos Black
Mods: • Magnex Cat-Back Exhaust • Smoked Corner Lights + Repeators • M3 17" Wheels • De-Baffled Air Box • AC HandBrake Handle and Gear Knob • DEPO Euro Epsiloids + Predator Chronium Rings • Chrome Interior bits •IE Poly-Urethane RSFMs • Kenwood Power Series Audio • Powder Coated e36 325 Front Callipers • Sports Seats | | | | | 08-23-2005, 11:22 PM | #7 | | Senior Member Join Date: Jun 2005 Location: St. Louis Posts: 138 |
you live on an island! how much driving could the average person do? its not like you ever have to drive across montana! __________________
97 sport | | | | | 08-23-2005, 11:46 PM | #8 | | Senior Member Join Date: Jan 2005 Location: Portland, Oregon Posts: 484 |
when i had th4e 4 cyl. I did nt have a problem using 87octane. Now im strictly on 92 diet. | | | | | 08-24-2005, 12:11 AM | #9 | | aka Stabby Join Date: Nov 2004 Location: Mead, CO Posts: 5,336 |
Quote: | Originally Posted by stormos $3 a gallon??!! ROFLMFAO!!!
its about 8-9 here. | that's right ... that's why we revolted!  should also be noted that it's 89 octane using the (R+M)/2 method. __________________ 1996 318ti, California package, 267k miles
current mods: bilstein sports, bavauto springs, e30 m3 LCABs, solid metal ball joints, bavauto RSMs w/reinforcements, e30 3.73 LSD & halfshafts, supersprint cat-back exhaust, turner rear sway bar reinforcements, IE poly subframe & RTABs + camber/toe kits, powdercoated e36 32x front calipers, sport mirrors, H&R 28mmF/19mmR sway bars, x-brace, auto solutions SSK w/poly bushing upgrade, BMW CD43 head unit, DICE HD Radio w/iPod integration and "stealth" HD antenna, staggered style 68s, orange electronic TPMS, leather arm rest, JT Designs metal undertray
acquired and awaiting install: heated seat kit, cali top switch relo, lumbar support kit, park distance control kit, heated washer nozzle kit, m-coupe rear subframe, trailing arms, differential, and halfshafts, m-coupe front/rear brakes with master cylinder, under hood light kit, mud flaps, rear sun blind, auto-dimming rear view mirror, tilt steering wheel retrofit, apexcone 5000K HIDs with 55W ballasts
2002 X5 4.4 Sport Package, 53.5k miles
Current Mods: e46 m3 steering wheel | | | | | 08-24-2005, 01:52 AM | #10 | | Site Moderator Join Date: Feb 2005 Location: Naples, Florida Posts: 238 |
I'm all 93 octane . I don't think I have ever used anything lower than that on my car or my Mercedes. Then again the car says it should take 89 octane but, $2.50 a gallon isnt all that much for 93 octane so why go lower? __________________ 
Nick
1995 BMW 318iC.
Modifications by: Understeer.com, M3 Aerodynamics, Bilstein, Stromung, Turner Motorsports, Bavarian Autosport and Downing Atlanta Superchargers. | | | | | 08-25-2005, 05:13 PM | #11 | | Senior Member Join Date: Mar 2005 Location: Portland Or Posts: 2,666 |
Because the engine makes more power on the octane its designed to run on?
Because its a waste of money to go higher?
Thats the 2 best reasons I know of...
Engines produce the most horsepower just and I mean just below the knock point.
Most premium fuel has extra ethanol to bump the octane(Now that MTBE is gone),
that means worse mileage as well.
Dave __________________
Dave - PDX
1995 318ti - Active Black and Tan.
2005 330xi - Mtech 1 - 6spd - Orient Blue/Black | | | | | 08-25-2005, 05:45 PM | #12 | | Senior Member Join Date: Jun 2005 Location: St. Louis Posts: 138 |
Quote: | Originally Posted by pdxmotorhead Because the engine makes more power on the octane its designed to run on?.....Engines produce the most horsepower just and I mean just below the knock point. | The way I understand it, a higher octane level (AKI) translates simply to higher compression allowance before the gas spontaneously combusts (knocking). You want the gas to be able to withstand the engine's max compression, and to combust when the plug fires, but not before. So I fail to see how using gas rated higher than recommended will harm performance in any way. It withstands the max compression, and ignites w/ the plug. It is a waste of money, but not a performance inhibitor. __________________
97 sport | | | | |
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