Will it hurt my engine or not?

[Saxwing1988]

The main thing it will hurt is you wallet. I have heard you can get a little carbon build up using higher octane fuel than needed, but one tank would not be a problem. As RonD indicated, your compression ratio is high enough that you could benefit from it in gas mileage and possibly even a little in performance.

I agree. I had a gmc jimmy as my first car and I always put in ransom shit. If I had money I did premium if not just 89 and I noticed no difference and the car made it till like 220k till a head gasket went out. I even put trick in it a few times just goofing around

 

[Uncle Gump]

@Saxwing1988

I edited your post...

In the future... please be mindful of the language.

Carry on...

 

[Saxwing1988]

@Saxwing1988

I edited your post...

In the future... please be mindful of the language.

Carry on...

Sorry habbit

 

[Pix3L8]

My 4runner askes for 87 but can run on 91 interchangeably according to toyota. The only REAL difference as stated a few times in this thread is the ignition timing being advanced or retarded by the knock sensor. Unless the vehicle explicitly states "super unleaded" you are good to run 87. Octane rating is the fuel's resistance to preignition, higher value is more stable against compression or pre-ignition (fact check me on that). If your vehicle senses the wrong octane the knock sensor kicks in and changes the timing to avoid damage to the internals. The only time higher octane is needed is USUALLY in high compression setups 10:1 and up.

 

[Saxwing1988]

online it says if you need premium you have to put in premium but I mean I have an srt4 that says premium only and I put regular in a few times and nothing happened besides it probably burned threw it quicker. Online it only says it matters if your car says it only takes premium but I never really believed it. There’s gas stations where I live that lie about the octane levels so I mean most times your not even putting in premium when you do choose premium.

 

[scotts90ranger]

octane is the resistance to preignition basically, and you mostly only get preignition when using power, you're likely to use more regular than premium in the mpg department if your engine needs it because most cars that need it have knock sensors that are hopefully tuned correctly to detect spark knock which reduces spark advance which usually transfers to less torque to to get the same power it takes more throttle which is more air which is more fuel

If that makes any sense...

 

[ekrampitzjr]

Octane is a heat rating
A gallon of 87 octane and a gallon of 93 octane have the same energy stored ...

Obviously since there are fuels with over 100 octane the percentage thing is just used as a example of "how it works"

In theory the maximum octane rating should be 100, meaning the fuel is 100% octane. The 87, 89, 91, 93, etc., represent percentages of octane in a mixture of heptane (which supposedly is so bad that it causes knock in every gasoline engine) and octane. So how is >100% possible? Back when Sunoco 260 and other gasoline was available with over 100 octane, each additional percentage point was defined as having so many grams of tetraethyl lead (TEL) added per gallon. TEL was known to increase octane by a particular amount. It made octane ratings of 104+ possible back in the muscle-car days.

Other types of fuels, such as alcohol used as racing fuel, were tested for knock resistance against this standard. That's how racing alcohol gets an "octane" rating of over 110. Some long-ago aviation gasolines had ratings as high as 130, but those were blends with lots and lots of TEL.

Public service note: tetraethyl lead is nasty, toxic stuff, and we're far better off for not having it added to automotive fuel any more. Aviation gasoline still has it, but there are plans to replace 100LL with a special blend without TEL.

 

[ekrampitzjr]

Duffy is correct. Cetane is the diesel equivalent of octane.

Cetane ratings for diesel fuel have lower numbers than do octane ratings for gasoline. In North America 40 is minimum and is what you usually see at diesel pumps. Some "premium" diesel fuels go as high as 50. In Japan the minimum is 45 and in Western Europe 51, and these are legal standards. Fun fact: that means our stuff cannot legally be sold as diesel fuel in Europe. The cetane rating is too low. Our 40–cetane fuel has caused problems for foreign auto manufacturers wanting to sell diesel vehicles here, because those were designed for 51.

I've hijacked the thread enough talking about fuel. Carry on.

 

[RonD]

Yes, if you ever get a chance read a bit about Thomas Midgley Jr

Brilliant engineer/chemist and often referred to as the one man that damaged the planet the most
He developed leaded fuel

He was also on the team that developed Freon 12(R12) using CFC's, the compound that destroys the Ozone layer

He worked for GM

 

[ekrampitzjr]

Tetraethyl lead is so toxic that anyone working around it at the facilities that made it had to wear a full "moonsuit" with respirator. TEL is an "organo-lead compound", and all of those are really bad news. It's nuts that the stuff was once added to most gasoline and stayed that way for decades. I think it might have been the reason gasoline once had the amber color, but I could be wrong. Straight gasoline is basically clear, as you see today.

Back to the subject of the thread, I've had the same experience some others here report with my 4.0 SOHC. It runs okay on 87 octane, but really seems to prefer the better stuff. Filling with 93 v. 87 is only a few dollars' difference per tank since 87 is so high now.

 

[don4331]

87 octane gasoline is the equivalent of 87% iso-octane and 13% heptane. How the guys at the refinery actually achieve that number is black magic. Because the refineries are mixing a whole lot of aromatics, the energy content can vary (and actually heptane has more energy than iso-octane)

Iso-octane is actually 2,2,4 - Trimethylpentane and has rating of 100 (Octane is where the Snow White and the 7 dwarves (carbons) are all in a row with a pail in each hand (hydrogen) with Snow White balancing one pail (hydrogen) on her ...s and Dopey having an extra pail (hydrogen) on stick up his... See Chemistry can be fun) 2,2,4 - Trimethylpentane is a messy combination.​

Heptane has a rating of 0.​

Having a rating better than 100 just means it is better than iso-octane. And a lot of compounds are better - ethanol (grain alcohol) is about 110, propane about the same, my favorite - triptane, or 2,2,3-trimethylbutane about 180.
Just because a rating is 0 (or less) doesn't mean it won't run in a spark ignition engine, just that it would a very low compression engine.

Back to the the black magic, when refineries were allow to use tetraethyl lead, they would refine gasoline to say 80 octane, then add TEL to raise rating to 87 as it was cheaper to add lead than to refine a better product. The stuff we pumped in 70's at my dad's garage had ~2 grams/gallon. That lead did a nice job of coating the valve seats, so manufacturers could run the valves directly on cast iron heads, so they were in no hurry for it to be replaced. It's that coating of valve seats that prevents it from being removed from Aviation fuel.

And we can thank catalytic converters for getting lead removed from gasoline.

I don't usually subscript to conspiracy theories, but we note Dupont's patent for R12 expired when the Ozone crisis was worst. Then right after we all to moved to R134a, all the noise about hole over Australia died off. And it should have been getting worse for next decade because the volume of historic R12 out there. Just saying.