What octane should I run?

[Skid Vicious]

LOL, I'm just interested to see some of the responses here. 87? 91? 93?
Asking this question on my motorcycle forum is like poking a hornets nest with a flaming stick. Sure to get you stung with the hundreds of replies.
Are there still people here that think 93 will get you better power or mileage?

 

[kunar]

LOL, I'm just interested to see some of the responses here. 87? 91? 93?
Asking this question on my motorcycle forum is like poking a hornets nest with a flaming stick. Sure to get you stung with the hundreds of replies.
Are there still people here that think 93 will get you better power or mileage?

unless your engine pings under load (predetonation) theres no reason to go for the expensive stuff. you wont get any better power or mileage with 93 vs 87. now some engines that run advanced timing may need a higher octane to prevent pinging, but the engine is also tuned for more power. your engine (from the factory) is tuned to run on 87.

 

[alaskan155]

i run 85 in my f150 and 87 in my bike, don"t have 93 here but high octane helps a little in the higher elevation as far as power, but not worth the money

btw im at 6,000 feet above sea level

 

[Shran]

The main things to remember here are a) use whatever octane is recommended for your vechicle, and b) gas with ethanol octane enhancers will reduce your gas mileage.

 

[Wicked_Sludge]

your engine is tuned to run on 87. it has no way to activly monitor what grade of fuel is in the tank, so therefor it cannot adjust the engine to take advantage of the higher octane fuel and you will gain no power or mileage with it.

older trucks with a distributor can be manually adjusted to accept higher octane. newer trucks require a programmer to adjust the engine electronically.

i run 97 in my truck with 25 degrees base timing and saw a 2MPG increase (no noticeable power), which is above the break even point....so im actually saving money by running top-grade fuel.

 

[LearjetMinako]

I've always run 87 octane in the Ranger. Maybe once a year, I'll fill up with Shell V-power 91. On my Kawasaki KLX250s, I always fill up with 91 octane. Runs smoother with it at lower speeds.

 

[Destroyer000]

i run 89 in mine. seems to run smoother an not ping when on the gas.

 

[shadetree]

unless your engine pings under load (predetonation)

There is no such thing as predetonation. It is pre-ignition, or detonation. You hear detonaton(pinging), and it can be damaging to the engine. Pre-ignition is not always heard, and will quickly destroy the engine.

Using higher octanes than intended in an engine can cause a loss in power due to the fuel burning slower. That is what the octane does, slows down the burn rate to prevent detonation at higher compression ratios, and advanced timing.shady

 

[shadetree]

i run 97 in my truck with 25 degrees base timing and saw a 2MPG increase (no noticeable power), which is above the break even point....so im actually saving money by running top-grade fuel.

Why in the world would you do that. 97 octane is race grade fuel, and 25 degree base advanced?????????? Race engines don't use that much advance. It isn't the base advance that is of concern, but total advance.shady

 

[Wicked_Sludge]

There is no such thing as predetonation. It is pre-ignition, or detonation. You hear detonaton(pinging), and it can be damaging to the engine. Pre-ignition is not always heard, and will quickly destroy the engine.

furthermore, running a higher octane fuel than specified by the manufacturer is a band-aid. it will help the problem until you can find the cause, but it doesnt get rid of whatever is causing the problem.

Why in the world would you do that. 97 octane is race grade fuel, and 25 degree base advanced?????????? Race engines don't use that much advance.shady

seeing how it comes from the pump at the local shell station, 97 is a high grade pump gas
i filled the tank with premium, then advanced the timing until i got detonation under load, then backed it off 5 degrees. 25 is just what i ended at. my idle quality is unchanged and my fuel economy is improved. power wasnt noticeably changed one way or the other.

 

[Nipplechops]

I run 87 octane in my current truck 99.999% of the time. If I am going to be hauling my camper and towing a trailer through the mountains in the heat of summer, I'll run midgrade to be on the safe side.

In my dirtbikes I run premium. If the weather is hot and I am navigating tight trails, I'll run 93 octane in them if I am near a Chevron.

I run the highest octane I can find in my Shovelhead. Fuggin' thing detonates itself into oblivion if I don't.

 

[Evan]

I run 87 in the 4.0 OHV. When wheelin I'll fill up on 89, as I have the engine under load at real low RPM and want to reduce detonation.

My Mustang Cobra takes 93, with none of that ethanol crap recommended.

 

[kunar]

There is no such thing as predetonation. It is pre-ignition, or detonation. You hear detonaton(pinging), and it can be damaging to the engine. Pre-ignition is not always heard, and will quickly destroy the engine.

learn something new every day... i wonder how many other people caught my mistake

 

[Hawker]

87 octane is the most powerful fuel for your truck. The higher octane numbers don't relate to being more powerful, they refer to burn or explosion time. Most of our vehicles have a computer managed ignition that keeps it in the proper range. Change the fuel and the computer will modify the timing so it fires at that same right time. There is no point to doing this. You're not getting more power or any other benefit, but making the oil company a lot happier.

 

[Wicked_Sludge]

Change the fuel and the computer will modify the timing so it fires at that same right time.

this isnt correct. as i already said, most vehicles (rangers included) dont come with any way of activly detecting what grade of fuel is in the tank, and thus they have no way of taking advantage of a higher octane fuel. there are ways to modify the computer to increase power and/or mileage with a higher octane, but it isnt automatic and just dumping a higher grade fuel in the tank with an unmodified computer does nothing but waste money.