Whos ran 87 in there car?

[tbromley]

Yes, it is.

Keep in mind, though, that the "reduced performance" applies to mileage as well as acceleration. I wouldn't recommend using regular fuel as a cost-saving measure, since any savings on the price may be more than offset by a decline in mileage. I would only use regular if you're out in the middle of nowhere and all they have is regular, to keep from getting stranded.

I would agree with Ken on this but that would be when the difference in cost between regular, silver and hi test was a few cents - now with hi test costing as much as 15+ cents more per or maybe 20 - it may not prove out to be a trade off for the additional expense of hi test. I did a fuel comparison test as a science project cents per mile and miles per gallon - back when the difference was very slight for the cost and hi test was 100 octane - it's not like that anymore. I very much doubt a test like that would find that hi test was less "cents per mile".

Just a guess but you will of course realize a loss in performance. But for most in town driving on a daily basis if you have 89 octane as opposed to 93 - will there be a big diff - I doubt it. We have 87 - 89 - 93 here in GA and around town we have 10% ethenol - that has lowered mileage too - so how can we tell in a major metro area? Gotta get out there in the boonies where there is no requirement for ethenol. Then you might see some difference. Go to the airports - small local one- and get some flight fuel - might see a big difference there.

 

[FogCityNSX]

Seeing that the price difference between a full tank of 85/87 and 91/93 is under $4, I see almost no point in even pumping the lower octane if proper octane is available.

I go through one tank every 2-3 weeks or longer.

 

[nsxtasy]

I would agree with Ken on this but that would be when the difference in cost between regular, silver and hi test was a few cents - now with hi test costing as much as 15+ cents more per or maybe 20 - it may not prove out to be a trade off for the additional expense of hi test.

It's easy to calculate. For example, let's say regular gas is $3.60 and premium is $3.80. And let's say your NSX gets 20 mpg with premium and 18 mpg with regular. Then with premium fuel every 20 miles will cost you $3.80, or $3.80/20 = 19 cents a mile, and with regular fuel every 18 miles will cost you $3.60, or $3.60/18 = 20 cents a mile. So regular is more expensive than premium. (If you assume 20 mpg with premium and 19 mpg with regular, then the cost per mile is almost exactly the same.)

The higher fuel prices are, the more the penalty in gas mileage will cost you, as long as the differential between regular and premium stays constant. If those prices go up by $1 or $2 a gallon with the difference remaining 20 cents, the advantage of premium increases.

 

[tof]

It's easy to calculate. For example, let's say regular gas is $3.60 and premium is $3.80. And let's say your NSX gets 20 mpg with premium and 18 mpg with regular. Then with premium fuel every 20 miles will cost you $3.80, or $3.80/20 = 19 cents a mile, and with regular fuel every 18 miles will cost you $3.60, or $3.60/18 = 20 cents a mile. So regular is more expensive than premium. (If you assume 20 mpg with premium and 19 mpg with regular, then the cost per mile is almost exactly the same.)

The higher fuel prices are, the more the penalty in gas mileage will cost you, as long as the differential between regular and premium stays constant. If those prices go up by $1 or $2 a gallon with the difference remaining 20 cents, the advantage of premium increases.

I'm sure someone would have soon pointed out that the actual difference between 86 and 93 octane (where available) is closer to 25-30 cents these days, had I not made the point in this post. But even with that price gap the savings from pumping cheaper gas are at best mostly offset by the loss in mileage. This to the point where you might save a buck or two per fill-up, less than the cost of a decent cup of coffee. After paying what you did for the NSX, is it not worth a few pennies to enjoy the car's full potential?

 

[tbromley]

First of all I use hi test - I am not trying to sell anyone on the idea they should use high test. With that said this is just a hypothetical answer to a discussion of what is cheaper - hi test or regular - I would say that you can't really assume anything about mileage but would have to test the actual mileage under real life conditions and my point still is that the difference in cents per mile is almost not worth "calculating". The parameters are obviously easy manipulate. As Ken said that if you vary the mileage by one mile per gallon it becomes a moot point. I have no idea what the actual mileage would be and on top of that - when I did my comparison years and years ago - there was a difference between brands as well. We tested a range of fuels from all manufacturers or labels. Today that gap is so close except for real cheap gas - it most likely matters little as long as it's a "premium" type gas - as in one of the major companies like Shell, BP(Amaco), Exxon, Chevron. But what about Costco? Who knows.

It would be interesting to do a test with another car - not my NSX. I only use hi test from BP or Chevron or Shell. I don't know about QT it may be fine. Anyone care to chime in on QT or Costco?

 

[Miner]

YMMV.:biggrin:

 

[nsxtasy]

the actual difference between 86 and 93 octane (where available) is closer to 25-30 cents these days

That varies by location. At over 90 percent of the gas stations in the Chicago area, it's exactly 20 cents, and that differential has not varied for the past five years (although obviously the prices themselves have).

Today I filled up the MDX at Sam's Club, where prices were $3.609 for regular and $3.809 for premium. Other stations I passed had posted prices that mostly varied from $3.679/$3.879 to $3.759/$3.959.

And 86? Aside from higher elevations (e.g. Denver), regular gasoline is 87 octane throughout most of the country. Premium is predominantly 93 octane east of the Rockies (although there are some places with 92 and Sunoco sells 94) and 91 west of the Rockies.

 

[mlambert890]

Given how many exposes have been done on stations "blending gas" and outright scamming (where tests show that pretty much whatever you pay you're buying regular), I suspect that *everyone* has run on 87 or lower whether we like it or not at one point or another, and whether we religiously use ultra (I do) or not.

So while I think its a good idea to stick with the highest octane you can get (if the difference in 30 cents a gallon is a deal breaker, IMO you need to be honest with yourself and sell the "toy" car), I wouldn't be stressing if I accidentally filled 87.

 

[playswfire]

When I tested it, I found no difference between mileage with premium and regular, shell vs BP vs "Starvin Marvin" (took about a year) - 90% highway driving in a 240SX doing a randomized trial (unfortunately the data went with the 240).

Conclusion: to reduce cost, use the cheapest stuff available.

With regard to airport gas - you will be tempted to get the 100LL - the "LL" stands for "low lead" which means "some lead" so you may be in the market for some new cats.

The brand on the sign may not be the guy who refines the gas, it is common to see the same trucks making dropoffs at several differently branded stations, so you can't allways assume that the Shell station is selling something different than the QT or Racetrac or Kroger.

 

[tof]

OK...first off I think xtasy is almost certainly correct. Even though we are a little backward down here I'm pretty sure even in Mississippi regular is rated at 87 octane.

As to the price spread, it's a 20 cent hop from regular to premium at Sams, but at a local CircleK the spread is 28 cents.

My post regarding loss of mileage at lower octane was based on a personal test in a highly modified Galant VR4 running around 28 pounds of boost and driven hard. Most driving was in town at sea level. I was prompted to perform this test after reading a short article by Oscar Jackson in Car and Driver in which he described his own similar test in a supercharged Civic Si (IIRC), which vehicle he also no doubt drove pretty hard.

So your mileage may vary.

Further testing is absolutely warranted. If my NSX was a daily driver I would offer it up as a suitable mule for such testing, but given the limited miles the car sees it would be hard to remember to keep up with the mileage, especially given the limited storage capacity of my brain which is already heavily loaded with useless trivia.

 

[playswfire]

My test was with a stock, normally aspirated vehicle, probably makes a difference - computer has to make a lot of allowances for the reduced AKI in the highly modded vehicle running nearer the edge.

I was also not running hard, just cruising 80-90 mph for 300 miles each way; probably makes a bigger difference.

 

[nsxtasy]

When I tested it, I found no difference between mileage with premium and regular, shell vs BP vs "Starvin Marvin" (took about a year) - 90% highway driving in a 240SX doing a randomized trial (unfortunately the data went with the 240).

Conclusion: to reduce cost, use the cheapest stuff available.

That's a valid conclusion - but for the 240SX, not for the NSX.

On cars that are designed to use regular - like the 240SX - there's no benefit to using premium. So go ahead and use regular in such cars. (Off-brand gas tend to use different additives that may or may not be a problem.)

However, on cars that are designed to use premium - like the NSX - when using premium fuel there is a performance benefit that may include better mileage as well as acceleration. In some such cars, it can cause pinging (detonation) and eventually result in damage to the engine; I do not believe this is the case with the NSX, but it is the case with many other cars (including my MDX). So if your car is designed to use premium, use premium.

 

[Huck]

Now just to muddy the waters a bit--it is absolutely a fact that in my area of Central Ky "Louisville" most gasoline is trucked from 2 huge distribution centers on the west side of town. They supply just about any and every retailer and THEY set the PRICE to the retailer on a daily and hourly basis who in turn tweeks the price to the consumer. The quality of the fuel varies. Some get special addatives and some---?
A couple of years back the State of Ky had a contract with Marithon for gas for all their vehicles. They "all of a sudden" had a major problem with in-tank fuel pump failure due to some addative or lack of additive. They started a legal action and the case was settled out of court. Marithon Oil is a division of Ashland Oil that sells gas under several names ----.
I have not used their gas in any of my vhichles in years and have not lost one fuel pump but know people who have and have!! So, stick to the best "Shell, Mobil, Exon, etc." as the mileage you put on your exotic NSX is not the same as running the hell out of some el-cheapo dialy driver or commuter. Most of us are not pushing a ton of miles on our NSX so why take chances to save a few cents. It's really a no brainer to use the best (within reason) oil, batteries, tires, brakes, clutch, etc. as the cost of labor and parts on the NSX exceeds any potential savings of going cheap. My .02 and I'm sticking to it!! Huck:biggrin:

 

[IRVINFLA]

don't do it for more than an occasional tankfull. Years ago, i stopped using premium (as specified in owner's manual), for my bimmer, and fouled a plug.

however, on cars that are designed to use premium - like the nsx - when using premium fuel there is a performance benefit that may include better mileage as well as acceleration. In some such cars, it can cause pinging (detonation) and eventually result in damage to the engine; i do not believe this is the case with the nsx, but it is the case with many other cars (including my mdx). So if your car is designed to use premium, use premium.

+1.