# Premium Gas Required?? **URL:** \ **Category:** Factual Questions\ **Created:** [April 30, 2009, 3:01pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845 "2009-04-30T15:01:22Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![spifflog](https://avatars.discourse-cdn.com/v4/letter/s/c5a1d2/32.png) [@spifflog](https://boards.straightdope.com/u/spifflog)\ **Post date:** [April 30, 2009, 3:01pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/1 "2009-04-30T15:01:22Z")
I just bought a new car after ten years (yeah me!!). But it requires premium gas. What happens if I used plain old regular? I suppose that it will go 0-60 somewhat slower, but will it hurt the engine in the long run? ---
**Author:** ![Iggins](https://avatars.discourse-cdn.com/v4/letter/i/b9e5f3/32.png) [@Iggins](https://boards.straightdope.com/u/Iggins)\ **Post date:** [April 30, 2009, 3:21pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/2 "2009-04-30T15:21:01Z")
My Passat requires premium fuel. As I understand it, it’s the octane rating that is actually important. The engine is a higher output type, so requires higher octane. Does your car have a turbo? Which car did you buy? ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [April 30, 2009, 3:21pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/3 "2009-04-30T15:21:48Z")
Probably not, [according to experts:](http://www.usatoday.com/money/autos/2003-07-30-premiumgas_x.htm) > [@](#): > > “I personally use regular even though my owner’s manual says you’ll get better performance with premium,” says Lewis Gibbs, consulting engineer and 45-year veteran at Chevron oil company. He’s chairman of Technical Committee 7 on Fuels, part of the Society of Automotive Engineers (SAE) Fuels & Lubricants Council. Gibbs knows gas. > > “My wife runs midgrade (89 octane) in her car, and it’s a turbocharged engine” meant for 91-octane premium, he says. > > … > > “I go back and forth, and I’m hard-pressed to notice” whether there’s regular or premium in the tank, says Jeff Jetter, principal chemist at Honda Research and Development Americas. He drives an Acura designed for premium. > > … > > All Porsche engines are designed for premium, too, but it’s not available everywhere. “Our cars must be able to drive all over the world, and so we are able to run on regular,” says Jakob Neusser, director of powertrain development at Porsche’s research and development center in Weissach, Germany. “You don’t have to feel that a mechanical problem or anything else will happen” using regular gas, even in the highest-performance, regular-production Porsches. ---
**Author:** ![spifflog](https://avatars.discourse-cdn.com/v4/letter/s/c5a1d2/32.png) [@spifflog](https://boards.straightdope.com/u/spifflog)\ **Post date:** [April 30, 2009, 3:25pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/4 "2009-04-30T15:25:51Z")
It’s a Nissan 350Z roadster. Not a turbo. ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [April 30, 2009, 3:30pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/5 "2009-04-30T15:30:41Z")
I hate pinging, so I’ll continue to stick with premium for my Civic SI. ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [April 30, 2009, 3:42pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/6 "2009-04-30T15:42:18Z")
I had a Civic Si until someone totalled it. I never tried regular but I know others who did and it worked OK. ---
**Author:** ![YamatoTwinkie](https://avatars.discourse-cdn.com/v4/letter/y/cc9497/32.png) [@YamatoTwinkie](https://boards.straightdope.com/u/YamatoTwinkie)\ **Post date:** [April 30, 2009, 3:45pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/7 "2009-04-30T15:45:47Z")
see the CarTalk [FAQ](http://www.cartalk.com/content/features/premium/questions.html) on the subject ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [April 30, 2009, 3:56pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/8 "2009-04-30T15:56:21Z")
I don’t know about Nissans, but a Chrysler/Dodge/Whatever with a Hemi engine will run like a lame 3-legged dog on 85 octane. It will run, and it won’t blow up, but the engine computer will be adjusting things to minimize knocking and pinging. The end result is really bad fuel economy, rotten performance, and you wind up paying more for gas than if you’d bought 87 in the first place. ---
**Author:** ![crazyjoe](https://avatars.discourse-cdn.com/v4/letter/c/f14d63/32.png) [@crazyjoe](https://boards.straightdope.com/u/crazyjoe)\ **Post date:** [April 30, 2009, 4:22pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/9 "2009-04-30T16:22:22Z")
85 octane is sub-regular…87 is regular and 89 is mid-grade. depending on your location, premium is either 91, 93, or 94. Does your owner’s manual say it is REQUIRED or RECOMMENDED? If it’s required, I’d put in at least mid-grade, but probably premium. I mean, you bought a brand new roadster and now you want to cheap out on the gas? You will definitely notice more performance issues, perhaps knocking and pinging, and some hesitation, with regular. ---
**Author:** ![Tapioca\_Dextrin](https://avatars.discourse-cdn.com/v4/letter/t/3d9bf3/32.png) [@Tapioca\_Dextrin](https://boards.straightdope.com/u/Tapioca_Dextrin)\ **Post date:** [April 30, 2009, 4:27pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/10 "2009-04-30T16:27:03Z")
I’ve got a Subaru Forester with a turbo. There is no difference in gas mileage with mid-grade or premium, but regular gas about a 15% drop in the MPG. I’ll stick with the 89 octane stuff. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [April 30, 2009, 4:48pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/11 "2009-04-30T16:48:41Z")
First of all, completely ignore the words “regular” “mid-grade” and “premium”. Higher octane gas isn’t “better”. If you put high octane gas in a car designed for regular, you will get no benefit at all, and in fact the car may actually perform slightly worse. The octane rating is how compressible the gasoline is before it spontaneously combusts. Your car’s engine works by compressing the gasoline then igniting it with a spark from the spark plug. If you use too low of an octane gasoline for your engine, then the gasoline will combust before the spark plug ignites it, which is really bad for your engine. Modern computers have knock sensors and such that will adjust the engine so you probably won’t do any major damage to it (at least in the short term), but it’s not a good way to run your engine. You should always use gasoline with the octane rating specified in your user’s manual. Anything higher is wasting your money (and may perform worse) and anything lower may cause damage and will definitely cause bad performance. As crazyjoe said, read your manual carefully. My Cadillac recommends 91 octane but requires 89 or better. ---
**Author:** ![spifflog](https://avatars.discourse-cdn.com/v4/letter/s/c5a1d2/32.png) [@spifflog](https://boards.straightdope.com/u/spifflog)\ **Post date:** [April 30, 2009, 6:07pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/12 "2009-04-30T18:07:50Z")
As always, thanks for all the help. You are right. Spend $30 to $40K I shouldn’t quibble about an extra $200 per year in gas. Just wanted ground truth. ---
**Author:** ![whiterabbit](https://avatars.discourse-cdn.com/v4/letter/w/cab0a1/32.png) [@whiterabbit](https://boards.straightdope.com/u/whiterabbit)\ **Post date:** [April 30, 2009, 6:47pm UTC](https://boards.straightdope.com/t/premium-gas-required/494845/13 "2009-04-30T18:47:19Z")
> [@crazyjoe](#): > > 85 octane is sub-regular…87 is regular and 89 is mid-grade. depending on your location, premium is either 91, 93, or 94. All the regular around here is 85. I live at 5800 feet, which is apparently why. 87 is mid-grade. It confused the heck out of me when I moved here. My car (nothing fancy) runs just fine up here on 85. Just so ya know. ---
**Author:** ![SanDiegoTim](https://avatars.discourse-cdn.com/v4/letter/s/85e7bf/32.png) [@SanDiegoTim](https://boards.straightdope.com/u/SanDiegoTim)\ **Post date:** [May 1, 2009, 2:12am UTC](https://boards.straightdope.com/t/premium-gas-required/494845/14 "2009-05-01T02:12:03Z")
Use the lowest grade that doesn’t ping. ---
**Author:** ![Eleusis](https://avatars.discourse-cdn.com/v4/letter/e/f4b2a3/32.png) [@Eleusis](https://boards.straightdope.com/u/Eleusis)\ **Post date:** [May 1, 2009, 4:48am UTC](https://boards.straightdope.com/t/premium-gas-required/494845/15 "2009-05-01T04:48:11Z")
Well I’ll be damned. My '96 Acura is now relegated to midgrade unless I notice pinging or loss of MPG. Thanks, 'dope! ---
**Author:** ![The\_Atheist](https://avatars.discourse-cdn.com/v4/letter/t/5f9b8f/32.png) [@The\_Atheist](https://boards.straightdope.com/u/The_Atheist)\ **Post date:** [May 1, 2009, 4:55am UTC](https://boards.straightdope.com/t/premium-gas-required/494845/16 "2009-05-01T04:55:53Z")
> [@spifflog](#): > > I just bought a new car after ten years (yeah me!!). But it requires premium gas. What happens if I used plain old regular? I suppose that it will go 0-60 somewhat slower, but will it hurt the engine in the long run? Yes. The engine won’t run properly and you’ll get a carbon buildup. Pay the extra; be kind to your car, or trade it for a 1300cc. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [May 1, 2009, 10:33am UTC](https://boards.straightdope.com/t/premium-gas-required/494845/17 "2009-05-01T10:33:04Z")
> [@The\_Atheist](#): > > Yes. > > The engine won’t run properly and you’ll get a carbon buildup. I will believe the automotive engineers cited upthread who disagree with you. ---
**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\ **Post date:** [May 1, 2009, 11:07am UTC](https://boards.straightdope.com/t/premium-gas-required/494845/18 "2009-05-01T11:07:29Z")
> [@engineer\_comp\_geek](#): > > You should always use gasoline with the octane rating specified in your user’s manual. Anything higher is wasting your money (and may perform worse) and anything lower may cause damage and will definitely cause bad performance. I disagree with the perform worse part. Unless it is a very old car that requires manual tune-up, all engines should benefit from higher octane gasoline. With higher octane fuel, the ECU will retard the ignition timing and the closer the spark fires to TDC means more energy transfer to the pistons. Now granted, the difference for a naturally aspirated car with no other mods will be minimal, usually 1-5hp max. Turbocharged cars are better because the ECU will also raise the boost pressure and some cars will gain 10-20hp. ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [May 1, 2009, 11:10am UTC](https://boards.straightdope.com/t/premium-gas-required/494845/19 "2009-05-01T11:10:12Z")
Goodness. 19 posts in and no one has pointed out that [Cecil has addressed this](http://www.straightdope.com/columns/read/2565/whats-the-difference-between-premium-and-regular-gas)???