Type of Octane?

[eddiebauer18]

What type of gasoline do you use for your gigs? and does a higher grade improve anything?

 

[waskly]

lower mpg, cleaner engine. i got a discussion on this in some other thread.

 

[eddiebauer18]

really?? it lowers mpg???

 

[SeanEXP]

just remmeber octane rating refers to how much energy it takes to ignite(explode) the gas, and not how much energy the gas will give. using higher octane is just wasting money unless your driving a car which requires it like an aston martin which require it because it has a high compression engine..

the only real thing you will see a difference in using a higher octane than need is in your wallet

 

[Joe Dirt]

lower mpg, cleaner engine. i got a discussion on this in some other thread.

No, that is incorrect.

From the API-

Octane Levels
The most common levels of octane grade are 87 (regular), 89 (mid-grade) and 91-93 (premium). The octane number of the gasolines offered for sale are set by gasoline refiners and marketers based on their perception of the technical and competitive needs in the market. Federal and most state regulations do not regulate minimum octane values, only that the postings on the dispensers accurately reflect the octane number of the gasolines being sold.

Gasoline with a higher heating value (energy content) provides better fuel economy. Traditionally, premium gasoline has had a slightly higher heating value than regular, and, thus, provides slightly better fuel economy, but it is difficult to detect in normal driving. There can be even larger differences in heating value between batches of gasoline from the same refinery, between summer and winter volatility classes, or between brands of gasoline from different refineries because of compositional differences. The differences are small and there is no practical way for the consumer to identify gasoline with a higher-than-average heating value.

The way I see it, no difference, not worth the $$.


The only real difference you're going to see is with a 'Top Tier' gas. They run better/more detergents/additives than economy brands like Costco and WalMart supplied stations. SeanEXP is correct.

 

[eddiebauer18]

Ok, thanks for taking the time to explain this, and I know you guys probably seen the question Im about to ask ALOT, but how can I improve my gas mileage? F.Y.I im only pushing 10.4 MPG :-(, but I have an EVAP problem that needs to be taken care of. Also, changing a fuel filter can improve mileage correct?

 

[Joe Dirt]

and for the detergents- I used to buy for Crystal Flash in Grand Rapids. For the top tier gassers, all of their octanes had the same amount of detergents. Higher octanes did not contain any more or any less detergents. Only the economy brands contained less.

For mileage- the king is AlDive (RIP)

CLICK ME

 

[eddiebauer18]

Wow, now I dont have to burn a hole in my wallet, THANK YOU GUYS

 

[alexk]

I always used plus in my explorer in the colder climate, it kept the mpgs up around the same as they were in the summer (around 16 with the V8). I have done one tank of plus in my Jeep and I forgot to check the mileage but it seemed to last just as long as it did before the winter blend came along.

 

[Joe Dirt]

Found a cool article, thought I'd post it here...

CLICK

 

[94Eddie]

There is just one reason I can think of to use a high octane gas in your vehicle. It is to prevent pre-ignition. If your engine has a high compression ratio from the factory, or after a rebuild, then you might need high octane to run a decent timing level. If you want to bump up the timing for better performance and mileage then higher octane gas can let you do it. Also, engines that get a lot of carbon buildup in the combustion chamber can effectively have the compression ratio increased which causes pre-ignition. High octane gas can stop the pinging that might occur.

About all the higher octane gas does is burn slower through the use of additives. This is what prevents pre-ignition. Unless the engine can take advantage of this by running higher timing and/or compression, you are wasting your money.

Edit: Some engines have knock sensors that listen for pre-ignition. When knocking is detected by the computer it will reduce engine timing until it stops. This reduces performance and gas mileage. IMO, if anyone sees a difference in gas mileage running higher octane gas than the manufacturer specifies, it is probably from the computer increasing engine timing back to stock levels because the higher octane gas is preventing spark knock. This means the engine is running lean for some reason or there is carbon buildup in the combustion chamber that is increasing the compression ratio.