Premium Gas in 2.5 Altima Coupe?

[hn1204]

I know that they suggest unleaded gas in the 2.5 but would it hurt if i pump premium in mine? I want the most out of my engine and the best for it. I dont mine paying the extra 2 bucks for the best gas that is available at the gas station.

[mcheddadi]

I know that they suggest unleaded gas in the 2.5 but would it hurt if i pump premium in mine? I want the most out of my engine and the best for it. I dont mine paying the extra 2 bucks for the best gas that is available at the gas station.

Strait from http://www.consumerenergycenter.org/

What kind of fuel grade will have the power to place a beast in your gas tank?The answer, according to experts who study fuel efficiency in detail, is both regular and premium gasoline. And it would be a waste of money to favor premium over regular, especially in these times when gasoline prices are high, according to the experts.

Virtually nothing is gained by filling up with a premium or more expensive grade of fuel than the vehicle manufacturer has recommended, the experts say. And many of the same experts explain that drivers may not lose much performance from their cars by using a lower grade of fuel than recommended by the car manufacturer.

There is little difference in energy content of regular versus premium gasoline. They both contain about 111,400 British Thermal Units of energy per gallon.

The price difference, however, between the fuel grades is anywhere from 20 cents to 40 cents, depending on where you live in the United States. The experts' consensus goes against the long-held belief by thousand of drivers who fill up with premium only, or on every third or fourth trip to the pump. The idea is to fill up with premium every so often to clean out the engines or rev up the performance of older engines.

But according to the experts, this practice is like tossing quarters in a wishing well, since most engines are designed to operate on relatively low-octane regular unleaded gasoline.

Octane is defined as a fuel's resistance to knocking. There is no benefit if the octane is higher than what the engine needs. Engine knock occurs when fuel in a combustion chamber ignites before it should. This disrupts the engine's operation. But electronic knock sensors are now common and have nearly eliminated engine disruption.

The American Petroleum Institute says if you find that your car runs fine on a lower grade, there is no sense switching to premium. The Institute recommends following manufacturer's recommendation, but even those manufacturers say that it is more of a suggestion than a command.

If you want to read more, here:http://www.straightdope.com/columns/041008.html


Modified by mcheddadi at 6:18 PM 9/2/2007

[SHIFT_COUPE]

^ Nice information.

There is a lot of speculation on grades of fuel. Its all up to you. When I put $20 worth of gas in my car today 89 Octane was $3.07, 93 was $3.14. A 7 cent difference really doesn't bother me.

[generic808]

Because I have the V6, I have to use premium; however, two other cars I've owened in the past were four-bangers and I always used premium in them. Never, ever had any engine probs with either of them ('91 240sx and '94 SE-R) and they both went over 100K. I was the same as you and thought a couple of bucks per fill-up didn't bother me. If I was you, I'd just stick to the premium. That's just my opinion though because I'm sure many will disagree.

[LongBeachCoupe]

My mustang died 2 weeks ago...

Although the Altimas are made in USA, its still not American in my eyes...

I put regular gas in the car and it went 115k miles (2 transmissions, 4 emissions sensors)

I put piss-gas in my car... until they make them to last 200k miles! (i have a "4 banger" lol)

[royal]

Because I have the V6, I have to use premium

You don't have to. The manual says that you can use regular but you may not have full performance.

[guitarmn07]

You don't have to. The manual says that you can use regular but you may not have full performance.

Yet I always wonder... what does it mean by...'full performance'?? Like... does the efficiency of the fuel converting into usable energy decrease?? Does horsepower decrease? Does MPG decrease?? What is 'full performance'?

I'd like to know....thanks!

[tsigoloeg]

Yet I always wonder... what does it mean by...'full performance'?? Like... does the efficiency of the fuel converting into usable energy decrease?? Does horsepower decrease? Does MPG decrease?? What is 'full performance'?

I'd like to know....thanks!

The engine knock sensors will detect predetonation and dial back the spark advance. Result is slightly lower hp. Fuel efficiency is dependent upon too many variables to make a blanket statement of up/down/same. Under the simplest scenario a decrease in hp would result in a decrease in efficiency (mileage) under similar load conditions.

Premium vs. regular unleaded: remember that 'octane' is only a rating, the gasoline doesn't necessarily have more or less of the actual octance vs heptane. Lots of other chemicals may be added to increase the anti-knock capability of the fuel (i.e., the octane rating) namely alcohol. All gasoline is required to meet minimum cleaning additives (injector, carbon residue, etc) as dictated by the feds. Premium gasolines may or may not (but usually do, with the major brands) have higher than the minimum, regular will definitely not. 'Brand X' gas almost certainly will not.

[guitarmn07]

Awesome thanks!

Now for the next question... where do you guys buy your gasoline?? Do you guys look for the absolutely lowest price you can find, or do you have a station that you prefer, ie Exxon, Shell, Citgo, Chevron...etc

Some one told me not to buy from Wal-Mart b/c their gas is cheap (cheap as in lower quality...not cheap as in inexpensive). I'm sure all gas stations and their gasolines aren't of the same quality. Everything that is produced has different quality levels.

[SHIFT_2.5S]

All oil comes from the same place.

Shell V-Power ftw!

[guitarmn07]

All oil comes from the same place.

Shell V-Power ftw!

Yes, but when they process the oil, it's the process that may differ, no?

And I actually bought from Shell my last fill up...

I might do some research this weekend...

[SHIFT_2.5S]

You can't do anything about processing. The best thing to do is to not be paranoid and to just fill up with good gas. I doubt any of the big companies mix their oil with water.

[SHIFT_CR]

Same person who post this forum, just a different name.

Last night, after going 450miles and my tank almost empty, i went for my first fill up on my 2.5 altima at citgo. Cost me like 53 bucks to fill up 18 gallons for premium gas (2.94 a gallon), i was like got d*mn, it seems alot when you fill up on empty.

So this afternoon, when i fresh started up my engine, it was like choking for air. After like a sec or two of choking, then it started. I turned off the engine and the turned it back on. The second time it was fine. Anyone had this happening on there 2.5?

I'm questioning premium gas for my car now. If this happen again tomorrow, im switching back to unleaded.

[tsigoloeg]

Awesome thanks!

Now for the next question... where do you guys buy your gasoline?? Do you guys look for the absolutely lowest price you can find, or do you have a station that you prefer, ie Exxon, Shell, Citgo, Chevron...etc

Some one told me not to buy from Wal-Mart b/c their gas is cheap (cheap as in lower quality...not cheap as in inexpensive). I'm sure all gas stations and their gasolines aren't of the same quality. Everything that is produced has different quality levels.

We (wife & I) buy almost exclusively from Exxon and Mobil, but that is b/c we have an employee discount using the credit card, which knocks almost $0.21/gal off premium. But I used to buy ARCO when living in CA and Amoco when living in MN.

Wal-Mart gas is from Murphy Oil. They are a major petroleum company. Much of the reason that Wal-Mart gas is less expensive derives from the same reason that WM is cheaper for retail products: high-volume/low-margin sales (possibly including loss-leaders). It isn't 'lower quality' inasmuch as all gas must meet minimum detergent and reformulation requirements. As much as I dislike WM in general (for only visceral reasons) I'd say your friend's advice is based on urban mythology.

So, yeah, less expensive WM gas might contain fewer detergents and other additives that prevent carbon buildup and injector clogging, etc. But think about this: one major company advertises that "just 5 tanks" (or some similar small number) of their premium will clean it out. So, one could have the mentality that 'why should I pay extra for 5-10 years of premium gas that can be fixed after a mere 5 tanks when/if a problem related to lower detergent finally shows up?' Given that premium is ~$0.25/gal higher and an average driver will use 500-750 gal/yr, well you see that adds up to real money over the 5-10 years that a problem might take to develop. A middle-of-the-road approach might be to buy premium once every 5 or 10 fillups.

PS - Yes, I do put the premium in my 3.5SE coupe!

[SHIFT_CR]

I dont think the 2.5 can handle premium gas. Ever since i pumped premium, it always choke when i try to fresh start it every morning.

[SHIFT_2.5S]

I dont think the 2.5 can handle premium gas. Ever since i pumped premium, it always choke when i try to fresh start it every morning.

The manual says mid-grade. I wouldn't put in any other. You can mix sometimes with V-Power if you want the cleaning effects, but put in mid-grade for the most part.