# Premium Gasoline **URL:** \ **Category:** Factual Questions\ **Created:** [April 12, 2000, 4:06pm UTC](https://boards.straightdope.com/t/premium-gasoline/10354 "2000-04-12T16:06:00Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![GasDr](https://avatars.discourse-cdn.com/v4/letter/g/ba9def/32.png) [@GasDr](https://boards.straightdope.com/u/GasDr)\ **Post date:** [April 12, 2000, 4:06pm UTC](https://boards.straightdope.com/t/premium-gasoline/10354/1 "2000-04-12T16:06:00Z")
Why do some newer cars ‘require’ that you put premium gasoline in them? Will it be bad for the car to put regular gas in it? I’m too cheap to pay for premiuim. ---
**Author:** ![sethdallob](https://avatars.discourse-cdn.com/v4/letter/s/e36b37/32.png) [@sethdallob](https://boards.straightdope.com/u/sethdallob)\ **Post date:** [April 13, 2000, 5:55am UTC](https://boards.straightdope.com/t/premium-gasoline/10354/2 "2000-04-13T05:55:00Z")
In general, yes. The extra octane in the premium gasoline prevents knocking and pinging in high performance engines. Believe me, the extra $1 you pay for premium will be a lot less than a new car 30,000 miles before its’ time. ---
**Author:** ![DougC](https://avatars.discourse-cdn.com/v4/letter/d/7feea3/32.png) [@DougC](https://boards.straightdope.com/u/DougC)\ **Post date:** [April 12, 2000, 9:59pm UTC](https://boards.straightdope.com/t/premium-gasoline/10354/3 "2000-04-12T21:59:00Z")
- - - What cars have you heard “require” it? I am curious because only (usually) foreign sports cars with very small, very high-power engines really need it. Brands like Ferrari, Lotus, + others. - - - One thing to keep in mind about premium gasoline is that (in the US, anyway) it is _cleaner_ than the cheaper stuff. Raising the octane level doesn’t cost squat; the real price difference comes from adding heavier petroleum by-products to the mid-grade fuel, and more so to the lowest-grade fuel. The by-products are cheaper than real gasoline but will still burn, just not real well; some cars will run rough on cheap gas. Wether this _hurts_ the car I don’t know. With modern computer-controlled engines, it might not be a great idea. - - - Fuel distributors (the companies gas stations buy gas from) sell several different types of gas for each octane rating, so all “92 octane” gasoline isn’t the same. The cheaper types of fuel are diluted with more by-products (i.e., “crap”) - it’s a way of cutting fuel (and fuel price). - MC ---
**Author:** ![Raza](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/raza/32/213_2.png) [@Raza](https://boards.straightdope.com/u/Raza)\ **Post date:** [April 12, 2000, 10:12pm UTC](https://boards.straightdope.com/t/premium-gasoline/10354/4 "2000-04-12T22:12:00Z")
> [@](#): > > What cars have you heard “require” it? Lexus LS400, for one (4L V8, 6500 rpm redline). ---
**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\ **Post date:** [April 13, 2000, 1:29am UTC](https://boards.straightdope.com/t/premium-gasoline/10354/5 "2000-04-13T01:29:00Z")
generally any V8+ with 300HP+ will usually require premium octane fuel. of course, the vehicle will still run on a lower octane fuel, but you’re asking for problems. ---
**Author:** ![Padeye](https://avatars.discourse-cdn.com/v4/letter/p/a9a28c/32.png) [@Padeye](https://boards.straightdope.com/u/Padeye)\ **Post date:** [April 13, 2000, 4:03am UTC](https://boards.straightdope.com/t/premium-gasoline/10354/6 "2000-04-13T04:03:00Z")
Specifically it’s usually an engine with a higher than normal compression ratio that requires high octane gasoline. If you squeeze the fuel/air mixture a little too much it will sharply detonate , sometimes before the spark ignites it, instead of burning smoothly. This is how diesel engines are _supposed_ to work and why they make a clattering sound. Gasoline engines can be damaged by excessive engine knock. High performance ignition tuning and valve timing or duration can be factors as well. ---
**Author:** ![Mike\_Palmer](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@Mike\_Palmer](https://boards.straightdope.com/u/Mike_Palmer)\ **Post date:** [April 13, 2000, 4:30am UTC](https://boards.straightdope.com/t/premium-gasoline/10354/7 "2000-04-13T04:30:00Z")
These days, most cars have knock detectors which adjust the timing to eliminate pre-ignition knocking. The owners manual for my car (V6, 200HP) recommends high octane, but says it will run fine (and does) on regular. I’ve used high octane from time to time, and found no difference - even during hard acceleration. These aren’t scientific tests, but there’s certainly no highly noticable difference. One odd note: the engine does knock sometimes, but ONLY when I am accelerating while going around a long right hand turn. Left turns don’t do it, and making a right turn from a stop doesn’t. Thoroughly bizarre. Since I can’t explain it, I’m going to invest in one of those cow magnets. I’m sure it won’t do anything, but then I’ll have an explanation for the behavior. ---
**Author:** ![lamerino](https://avatars.discourse-cdn.com/v4/letter/l/5f9b8f/32.png) [@lamerino](https://boards.straightdope.com/u/lamerino)\ **Post date:** [April 14, 2000, 12:58am UTC](https://boards.straightdope.com/t/premium-gasoline/10354/8 "2000-04-14T00:58:00Z")
Read what the FTC has to say: \*\* [The Low-Down on High Octane Gasoline](http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm) \*\* ---
**Author:** ![GasDr](https://avatars.discourse-cdn.com/v4/letter/g/ba9def/32.png) [@GasDr](https://boards.straightdope.com/u/GasDr)\ **Post date:** [April 15, 2000, 5:40am UTC](https://boards.straightdope.com/t/premium-gasoline/10354/9 "2000-04-15T05:40:00Z")
The 2000 Nissan Maxima ‘requires’ premium. ---
**Author:** ![Rhythmdvl](https://avatars.discourse-cdn.com/v4/letter/r/85f322/32.png) [@Rhythmdvl](https://boards.straightdope.com/u/Rhythmdvl)\ **Post date:** [April 14, 2000, 6:12pm UTC](https://boards.straightdope.com/t/premium-gasoline/10354/10 "2000-04-14T18:12:00Z")
What about a motorcycle engine? Don’t think it should make a difference, but wondering all the same. * * * Once in a while you can get shown the light in the strangest of places if you look at it right… ---
**Author:** ![InutilisVisEst](https://avatars.discourse-cdn.com/v4/letter/i/d2c977/32.png) [@InutilisVisEst](https://boards.straightdope.com/u/InutilisVisEst)\ **Post date:** [April 14, 2000, 8:57pm UTC](https://boards.straightdope.com/t/premium-gasoline/10354/11 "2000-04-14T20:57:00Z")
> [@](#): > > Originally posted by Rhythmdvl: > \*\*What about a motorcycle engine? Don’t think it should make a difference, but wondering all the same. > \*\* My 1994 Honda Nighthawk (CB250) requires 92 or better. Of course, it’s a small, high-compression air-cooled aluminum engine. That makes it more susceptible to and more easily damaged by knocking. The rise in gas prices has actually made Premium a **better** deal than it used to be. Our stations have kept the same dime difference between grades, so the % difference in prices is now lower. Numerous other threads have debated the usefulness of “Premium” fuels, but some brands (like Chevron) put more non-crap additives (tip o’ the hat to MC) in the higher grades. I think it’s worth it on that basis, even if higher octane is not required for knock prevention in computer-controlled vehicles. * * * I lead a boring life of relative unimportance. Really.