I took my cousin's TSX to a Honda dealership today and was talking to this other guy who drove an Si. He said he puts Shell Nitro gas in his car and he's able to get 33MPG driving 70MPH on the highway with AC on... Any validity to using this gas?

 

It could be he normally used cheap gas with minimal detergents in it, and the Top Tier Shell gas with lots of detergent is cleaning out his engine, thus making it run more efficiently.

Shell is generally okay gas. Make sure you buy from a station with lots of turnover, as I've had bad luck a few times with low-volume stations.

If you can find ethanol-free gas, kinda unlikely with your location in the corn belt, that offers noticeably better gas mileage than gas with 10% ethanol in it.

 

Yeah, I don't know about the whole nitrogen-enriched thing, but I buy Shell 'cause it's the only top-tier gas I can find locally. No difference in mpg since I switched from the cheap(er) stuff, but hopefully the better additives will make a difference long term. :shrug:

 

The only difference between gasolines is the additives period (and possible added ethanol). Gasoline is fungible. That means when an oil company ships a load up the pipeline, the put in a load and take out a load. They don't get the same gasoline out that they put in. That being said I stick with the top tier brands, mostly Shell, because thats what's near my home. Since the price of gasoline has gone down from it's high, most stations in my area have stopped adding ethanol.

 

You may be interested in Tom and Ray's column they just did on this:

Car Talk

 

I'm in the 10% Ethanol group here in NY. It sucks having to put that in my engine.

 

Probably valid because most premiums have higher energy contents than regular yielding better mpg. Hardly worth it though because a 5% gain in mpg that costs 20% higher per gallon is not economically justifiable. Premium does have move additives but you can get equal utilization by putting a can of injector cleaner of the non-alcohol type in your tank once a month.
At WallyWorld theirs costs about a buck a bottle so its economically justified.

 

Actually regular gas has more energy. The only advantage of premium is the flame front propogates more slowly in the cylinder because it's harder to ignite, which reduces pre-detonation, aka knock.

The L15 engine doesn't need premium, so there's no reason aside from the additives to run premium.

 

In cars that spec premium or in cars with excessive pinging on regular, premium will increase mpg due to timing advance. That's one reason I was glad to buy a car that ran regular. I always cringed at putting premium in my 9-5, but after calculating it out, I came out better financially by using premium.

But again, that car spec'd premium.

 

Not correct.
Having run hundreds of heats of combustion tests on a large number of gasolines I can assure you that it is very rare to have regular even equal premium in energy.
The components of gasolines that produce higher octane also have more energy, such as toluene vs heptane for example.
The flame front velocity in premiums is held back by additives as well as some components and to avoid detonation ahead of the flame front, which is knocking.
The Fit engine doesn't need high octane because the compression ratio is not high enough to raise compression temeratures to cause detonation. Honda correctly doesn't think an economy vehicle should use gasoline that costs a lot more than the mpg is worth.

 

A quick Google search energy content premium gasoline - Google Search
revealed that there is little change in total energy content between regular and premium. If anything premium as formulated today has slightly less energy due to what makes the flame front propagate slower. It's a difference of ~1000 BTU, or not enough to notice in our cars.

Whatever. Point is, the Fit doesn't need premium, there's no reason to run premium, save your dollars.

 

Again, untrue that the components that make up premium have less energy than those of regular.
Instead of unsubstantiated 'experts' (like the college profs who insisted that syntheic oil had no performance benefits even when they are watching dynomometer testing showing 3 to 5 hp gains and 2 to 4 % better fuel efficiency) both the American Petroleum Institute and I can prove slightly higher energy for premium fuels on the order of 2000 to 4000 BTU greater than regular, Thats why premium generally gets a small advantage in mpg; but as everyone knows, the cost increase is far greater than the energy increase, making the use of premium in a low compression engine a waste of money.
We didn't adjust our formulations and processing conditions for nothing.
You need to read those google submissions morwe carefully. Next time concentrate on what reputable sources like the API say. Next you'll be telling us adding acetone is a great way to increase mpg.

 

My friend used to do a newspaper rout drove it every day drove a week and avg the weeks gas together he tried chevron shell and arco arco and chevron same and e got 20 miles per tank more using shell I have done the same with similar resualts we both fill up on the shell on walnut and centrol