# What kind of fuel do you use in your regular vehicle? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [July 7, 2012, 7:15pm UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542 "2012-07-07T19:15:47Z")\ **Posts on this page:** 14\ **Page:** 2
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [July 8, 2012, 4:41am UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/21 "2012-07-08T04:41:31Z")
> [@Smashed\_Ice\_Cream](#): > > I get 93 because 94 doesn’t seem to be available anywhere I live. My car (Audi TT) had a big bright sticker saying premium fuel is required, not just suggested. > > Note (and I’m amazed I’m the first to point this out as it always comes up.) Higher octane gas in a car that doesn’t have a high-compression (performance type) engine is only costing you money. I don’t think the Civic Si’s have engines designed to need or really handle the compression and temp required for 93. > > Knocking or pinging is also not necessarily indicative of a need for higher octane fuel. Whatever fuel your owner’s manual tells you to put in your car is the octane rating that your engine is designed to run on. Knocking/pinging could quite easily mean something else that you’re ignoring while convincing yourself it’s ‘better’ when you use ‘better’ gas. (I liken this to homeopathy for cars.) > > As octane rating goes down, the fuel will detonate at a lower temperature/lower pressure. For high compression engines, it needs to have that little extra bit of leeway before combustion occurs in order to get maximum benefit from the fuel. In a car that doesn’t need it, I don’t see how higher octane could be helpful. I would assume it could cause carbon buildup and would reduce gas mileage. > > And holyhell, it’s expensive. Love my car. Loathe the gas pumps. My brother once told me that he ran a tank of premium through his truck every third time to increase the performance. :rolleyes: ---
**Author:** ![Ambivalid](https://avatars.discourse-cdn.com/v4/letter/a/a5b964/32.png) [@Ambivalid](https://boards.straightdope.com/u/Ambivalid)\ **Post date:** [July 8, 2012, 4:58am UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/22 "2012-07-08T04:58:04Z")
> [@Chefguy](#): > > My brother once told me that he ran a tank of premium through his truck every third time to increase the performance. :rolleyes: Oh I have no doubt that the majority of high-octane gasoline bought at gas stations is bought by people who think “premium” means “better for you car”. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [July 8, 2012, 5:13am UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/23 "2012-07-08T05:13:59Z")
> [@Chefguy](#): > > My brother once told me that he ran a tank of premium through his truck every third time to increase the performance. :rolleyes: To be fair, it was once true that they put a better additive and detergent package in the premium gas until the FTC made them put an end to that. So back in those days, running a tank of premium every so often might have made sense. Of course, it was probably 25 years ago that it was last true. The same sort of thing is sneaking back with a lot of stations carrying ethanol-free premium. It seems to me the only real reason to carry ethanol-free premium but still using it in the lower grades is to get people to buy a higher octane than they need to. I guess mayyyyyybe it’s so people can fill up their boats, but I’ve seen it in pretty landlocked areas. ETA: also, wow, I’m still the only 85-octane person? ---
**Author:** ![MsWhatsit](https://avatars.discourse-cdn.com/v4/letter/m/eb8c5e/32.png) [@MsWhatsit](https://boards.straightdope.com/u/MsWhatsit)\ **Post date:** [July 8, 2012, 5:17am UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/24 "2012-07-08T05:17:55Z")
> [@GreasyJack](#): > > ETA: also, wow, I’m still the only 85-octane person? Probably just because it’s not available in a lot of places. I just buy the lowest octane available, which around here is 87. If it were 85, I’d buy that. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [July 8, 2012, 5:25am UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/25 "2012-07-08T05:25:53Z")
> [@MsWhatsit](#): > > Probably just because it’s not available in a lot of places. I just buy the lowest octane available, which around here is 87. If it were 85, I’d buy that. I thought there’d be more high-altitude dopers though. How do you people stand the dangerously thick air down there?! ---
**Author:** ![MsWhatsit](https://avatars.discourse-cdn.com/v4/letter/m/eb8c5e/32.png) [@MsWhatsit](https://boards.straightdope.com/u/MsWhatsit)\ **Post date:** [July 8, 2012, 5:28am UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/26 "2012-07-08T05:28:36Z")
> [@GreasyJack](#): > > I thought there’d be more high-altitude dopers though. How do you people stand the dangerously thick air down there?! Don’t tempt me. I’m about one more 100-degree high-humidity day from packing my bags and heading for the mountains. ---
**Author:** ![pullin](https://avatars.discourse-cdn.com/v4/letter/p/c57346/32.png) [@pullin](https://boards.straightdope.com/u/pullin)\ **Post date:** [July 8, 2012, 10:34am UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/27 "2012-07-08T10:34:02Z")
My truck manual says 87, except when towing. I fill it with 89 when I’m going to be towing anything heavy. ---
**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:** [July 8, 2012, 4:28pm UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/28 "2012-07-08T16:28:49Z")
> [@Smashed\_Ice\_Cream](#): > > I get 93 because 94 doesn’t seem to be available anywhere I live. My car (Audi TT) had a big bright sticker saying premium fuel is required, not just suggested. > > Note (and I’m amazed I’m the first to point this out as it always comes up.) Higher octane gas in a car that doesn’t have a high-compression (performance type) engine is only costing you money. I don’t think the Civic Si’s have engines designed to need or really handle the compression and temp required for 93. Except that just like your vehicle mine is designed for it too (according to the manual). [28 page thread from a Civic SI forum](http://www.8thcivic.com/forums/mechanical-problems-technical-chat/75975-si-87-octane-gas-threads-merged.html). ---
**Author:** ![Procrustus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/procrustus/32/2994_2.png) [@Procrustus](https://boards.straightdope.com/u/Procrustus)\ **Post date:** [July 8, 2012, 5:43pm UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/29 "2012-07-08T17:43:40Z")
My Volt needs high octane because the gas sits so long in the tank. ---
**Author:** ![oreally](https://avatars.discourse-cdn.com/v4/letter/o/7ab992/32.png) [@oreally](https://boards.straightdope.com/u/oreally)\ **Post date:** [July 8, 2012, 9:14pm UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/30 "2012-07-08T21:14:30Z")
Whatever the lowest octane/cheapest one is available, which I have no clue what # it is or what “high altitude grade” means. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [July 8, 2012, 9:30pm UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/31 "2012-07-08T21:30:18Z")
I use **regular**. That’s the lever on the pump with the big R over it. I have no idea what octane it is. We only have three choices on our pumps here. Voted 87 octane because its the lowest in the poll. ---
**Author:** ![Covered\_In\_Bees](https://avatars.discourse-cdn.com/v4/letter/c/7ab992/32.png) [@Covered\_In\_Bees](https://boards.straightdope.com/u/Covered_In_Bees)\ **Post date:** [July 8, 2012, 9:55pm UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/32 "2012-07-08T21:55:53Z")
87, like my manual says to. Why was 86 not listed? It’s all over the damn place here for all the cheapskates. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [July 8, 2012, 11:33pm UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/33 "2012-07-08T23:33:33Z")
> [@Covered\_In\_Bees](#): > > 87, like my manual says to. > > Why was 86 not listed? It’s all over the damn place here for all the cheapskates. I know this goes against every tenet of auto ownership, but the manual is wrong, or at least incomplete in omitting how the octane requirements change with altitude. The general rule of thumb is that you can drop 1-1.5 octane number per 1000 feet of elevations. Running 86 in a car that calls for 87 above 1500 feet should be perfectly fine, although usually you don’t start seeing the high altitude gas until 2500-3000 feet or so. Running 87 octane when it’s the mid-grade gas is throwing your money away just as surely as running 89 octane at sea level. ---
**Author:** ![Cunctator](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Cunctator](https://boards.straightdope.com/u/Cunctator)\ **Post date:** [July 8, 2012, 11:35pm UTC](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542/34 "2012-07-08T23:35:14Z")
I don’t have a car. When I’m driving a rental vehicle I buy whichever petrol is the cheapest. [Previous page](https://boards.straightdope.com/t/what-kind-of-fuel-do-you-use-in-your-regular-vehicle/627542.md?page=1)