View Poll Results: what octane rating
89
9
7.83%
91
19
16.52%
93
81
70.43%
something else
6
5.22%
Voters: 115. You may not vote on this poll
octane rating
On The Tree
Joined: Nov 2005
Posts: 100
Likes: 0
From: Seattle
Octane is just a chemical added to resist pre-ignition...it's harder to light. Allows more optimal spark timing in a high compression engine. Our cars will run fine on any octane, since we have a detonation sensor, but with lower octane fuel, you're spark map will not be optimal and you will have less power. However, you may not notice less power unless you're driving WOT or near to it.
i just finished a one month gas mileage test. I use 93 for two weeks/tanks and 87 for two weeks/tanks. With the 93 I got an avg. of 16.4 mpg. With the 87 I got an avg. of 20.7 mpg. can anyone explain that?
TECH Addict
Joined: Nov 2005
Posts: 2,379
Likes: 2
I'm noticing my mileage running better with 91 sunoco octane over 94 octane. I was barely hitting 18's combined with 94 and with 91 I've gotten 20's for the same old trips to work. I have noted that a few rips to WOT pulling rolls/0-130 mph will DRAIN the gas tank. I did a quick 60 miles with 3 good hard WOT runs on some straights... I filled up and hit an all time low 14mpg... (I've been tracking mileage since I got this car so each trip to the station = full tank. WOT really really sucks down the gas like no tomorrow...
Teching In
Joined: May 2006
Posts: 24
Likes: 0
From: Ohio
Daily driving I only use 89 octane. At the track I use Shell 93. If your engine is built right and tuned right you have no need for the higher octane. It's only there to fight detonation. BTW, I run a first gen 383 sbc at 11:1 compression with no electronic controls/computers etc. It's my daily driver and runs 12.50's @ 110 N/A traction limited.
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I run whatever the highest octane avaliable is, which is usually 91-93. And yes WOT will dramitcally descrease gas mileage, but most of our cars wont' do too bad without getting on it much, I got 28MPG coming back from St. Paul when I first got my car.
On The Tree
Joined: Jun 2002
Posts: 155
Likes: 0
From: Doniphan, MO
Availability, more than anything else, causes me to use 89. Also, it is 10% ethanol. Now I know the manual says ">>>Do Not Use Any Fuel With Ethanol!" I've been using it for 5 years and about 60K miles with NO problems!
When I changed the plugs @ 70K, they were extreemly clean! Only reason I put in new ones was 'cause I alreadt had purchased them. (Denso Platinum). 89 does not ping, doesnot cause the engine to run hotter and gets me 26 MPG on the road.
The car is a daily driver, has been driven cross country 3 times and has 88K on it now. It uses 1 qt of oil every 2K miles.
My 2 ¢.
When I changed the plugs @ 70K, they were extreemly clean! Only reason I put in new ones was 'cause I alreadt had purchased them. (Denso Platinum). 89 does not ping, doesnot cause the engine to run hotter and gets me 26 MPG on the road.
The car is a daily driver, has been driven cross country 3 times and has 88K on it now. It uses 1 qt of oil every 2K miles.
My 2 ¢.
Originally Posted by BrianMSmith
Octane is just a chemical added to resist pre-ignition...it's harder to light. Allows more optimal spark timing in a high compression engine. Our cars will run fine on any octane, since we have a detonation sensor, but with lower octane fuel, you're spark map will not be optimal and you will have less power. However, you may not notice less power unless you're driving WOT or near to it.
in my fully modded 99 SS i only run 93-94 octane but in my dd 00 TA with no mods(cai & cat back) and A4 i use 89 and still knock down 28 mpg on the freeway. i get no knock and i can notice a slight performance increase with 93.
Tech Resident
Joined: Jan 2006
Posts: 5,117
Likes: 3
From: Philly
91 always. octane is not a power adder and you will gain nothing by going 93 other than a lighter wallet. only run 93 if it pings on 91 or 91 is not available.
the computer is tuned to run at 91 and above so you will also not gain gas mileage to justify the added cost of 93. any gas mileage increase you see is because of your driving style since you were likely looking for increased mileage and drove accordingly.
the computer is tuned to run at 91 and above so you will also not gain gas mileage to justify the added cost of 93. any gas mileage increase you see is because of your driving style since you were likely looking for increased mileage and drove accordingly.
Tech Resident
Joined: Jan 2006
Posts: 5,117
Likes: 3
From: Philly
Originally Posted by A BAD T/A
Availability, more than anything else, causes me to use 89. Also, it is 10% ethanol. Now I know the manual says ">>>Do Not Use Any Fuel With Ethanol!" I've been using it for 5 years and about 60K miles with NO problems!
When I changed the plugs @ 70K, they were extreemly clean! Only reason I put in new ones was 'cause I alreadt had purchased them. (Denso Platinum). 89 does not ping, doesnot cause the engine to run hotter and gets me 26 MPG on the road.
The car is a daily driver, has been driven cross country 3 times and has 88K on it now. It uses 1 qt of oil every 2K miles.
My 2 ¢.
When I changed the plugs @ 70K, they were extreemly clean! Only reason I put in new ones was 'cause I alreadt had purchased them. (Denso Platinum). 89 does not ping, doesnot cause the engine to run hotter and gets me 26 MPG on the road.
The car is a daily driver, has been driven cross country 3 times and has 88K on it now. It uses 1 qt of oil every 2K miles.
My 2 ¢.
read the gas pump. 89 is the "minimum octane required." it's 89 minimum for mid-grade here in NJ. that means your gas stations around your area may be running more than 89. i guess not everyone has the bare minimum?
i'm not saying that this is in fact the case. just if you run 89 in a different state you may see different results
contrary to popular belief, all gas IS NOT created equal...even with the same rating.
