Matt4949 Posted March 20, 2011 Share Posted March 20, 2011 (edited) Posted this on other forums, then found this one so I figured I'd post it up here as well. Hope it helps! I have 2001 Nissan Pathfinder LE 3.5 by the way. So since I've bought my Pathfinder a couple months ago, I've really been let down by the gas mileage. Locating any kind of specific info on what fuel I should use was surprisingly impossible, so I decided to run a little experiment and record my mileage first using regular 87 octane, then by running the "recommended" premium 93 octane (HOORAY CT). In the interest of keeping the figures represented here accurate, I would fill the tank when the gas light came on, only at Mobil or Shell, without topping off, approximately 18 gallons. Additionally, I made an effort to keep my driving consistent, 95% highway to work (cruise control at 62mph) and minimal city driving. Since I have bought the truck, I don't think she's seen 3k rpms. Now before anybody wants to jump down my throat, I realize there are many other variables that could have altered these numbers, especially with all the snow we got in the past few weeks, but I figured this process would give me at least ball park areas to make a more educated decision. Now bear in mind we still have that winter mix in the Northeast and I'd expect these figures to rise some in the summer. Using the equation: miles traveled per tank / price to fill tank = miles traveled per dollar Figures rounded to .100 where applicable Regular Fuel 87 Octane; Current Price: $3.81 18 gallons * $3.81 = $68.58 Price to Fill 242.5 miles / $68.58 = 3.536 m/$ 254.1 miles / $68.58 = 3.705 m/$ 247.6 miles / $68.58 = 3.610 m/$ 256.9 miles / $68.58 = 3.746 m/$ Average: 3.649 miles per dollar 242.5 miles / 18 gallons = 13.472 mpg 254.1 miles / 18 gallons = 14.117 mpg 247.6 miles / 18 gallons = 13.756 mpg 256.9 miles / 18 gallons = 14.272 mpg Average: 13.904 miles per gallon It is also worth noting that I waited a few tanks in between to allow the knock sensor to adjust to running the premium fuel. (Much thanks to Chuck Tribolet!) Premium Fuel 93 Octane; Current Price: $4.11 18 gallons * $4.11 = $73.98 Price to Fill 262.4 miles / $73.98 = 3.547 m/$ 261.6 miles / $73.98 = 3.536 m/$ 256.3 miles / $73.98 = 3.464 m/$ 260.7 miles / $73.98 = 3.524 m/$ 261.2 miles / $73.98 = 3.531 m/$ Average: 3.520 miles per dollar 262.4 miles / 18 gallons = 14.578 mpg 261.6 miles / 18 gallons = 14.533 mpg 256.3 miles / 18 gallons = 14.239 mpg 260.7 miles / 18 gallons = 14.483 mpg 261.2 miles / 18 gallons = 14.511 mpg Average: 14.469 miles per gallon So taking a look at these numbers broken down, we can see that although you most certainly get worse fuel efficiency running regular fuel versus the premium, you in fact are spending less money to drive any given amount of miles (albeit the actual difference is minimal) on the regular octane. With that being said, my truck has 119,000 miles on it now, and I will continue to run the recommended premium fuel. This is because I find the actual amount of difference in miles per tank (about 9) and cost to fill (about $5) to be negligible. Also, and here's the key reason why recommended is no longer in quotation marks, when running the regular fuel that VQ felt like a tired old engine with 100k+ miles on it. However with that premium fuel, she feels light on her feet and peppy from a stop. Personally, after driving with both fuels back to back, the difference is incomparable. This summer I'm planning to do a full tune-up as well as possibly a CAI to try to bump these numbers, but obviously I will strictly be running the premium fuel at that point. Thanks for reading! Hope it helps some who were unsure about what fuel to use like me. Edited March 20, 2011 by Matt4949 Link to comment Share on other sites More sharing options...
Howie Posted March 20, 2011 Share Posted March 20, 2011 I get 15-16 mpg running 91 octane in my 01 SE M/T 4WD. Link to comment Share on other sites More sharing options...
Phantom01Pathfinder Posted March 20, 2011 Share Posted March 20, 2011 this is a good post! nice info of price breakdown and comparison. Link to comment Share on other sites More sharing options...
Kingman Posted March 20, 2011 Share Posted March 20, 2011 Octane is resistance to burning. It contains no more or less energy. Higher compression engines and/or engines with highly advanced timing require premium octane fuel. Running 87 octane in an engine designed to run 93 octane can lead to pre-detonation or "knocking." The engine's computer sees this and retards the timing until the knocking stops, which reduces power and fuel economy. It also amuses me when people say they put premium in their tank when it's not required because "it's better for my engine." It's entirely a waste of money and the engine can't actually burn all of the fuel entering the combustion chamber per power stroke. Usually you'll see worse mileage running higher octane fuel than what's required. Link to comment Share on other sites More sharing options...
Tungsten Posted March 20, 2011 Share Posted March 20, 2011 Yep, you have to run what the engine has been designed for but regular fuel does have more energy in it than premium fuel. If you put premium into a car designed for regular it could be more hesitant and get less gas mileage. If you put regular into a car designed for premium then the engine can have a risk of detonation because of the increased amount of compression and compressing "too much" energy which will make the ECU retard the timing (for safety) and decrease the gas mileage. Link to comment Share on other sites More sharing options...
adamzan Posted March 20, 2011 Share Posted March 20, 2011 Holy @!*% only 14 mpg out of that truck. I get better than that in my 3.0! I bet a tune up will make it better, maybe you have a lazy/dead o2 sensor or something. Link to comment Share on other sites More sharing options...
Tungsten Posted March 20, 2011 Share Posted March 20, 2011 A VQ will typically get 14 mpg. Think about it, that thing is full time 4x4 and heavy. Link to comment Share on other sites More sharing options...
psychopathy Posted March 20, 2011 Share Posted March 20, 2011 I just switched back down to 87octane and didn't notice a change in my mileage. I get 16 mpg in my 03 with either grade. The fuel door and manual say that premium fuel is "recommended for maximum performance". I had no knock or hesitation when I made the change, although I did run about 4 tanks of mid-grade to kind of step it down. I've got 129,000 miles on it and I'm getting ready to change the plugs, flush the transmission, and changed the rear diff. oil. Everything else has been done as far as tune-up is concerned. Runs fine on the 87 octo..... Link to comment Share on other sites More sharing options...
Kingman Posted March 20, 2011 Share Posted March 20, 2011 You didn't notice any knocking because the computer adjusted the timing. Older vehicles requiring premium will more than likely ping. Link to comment Share on other sites More sharing options...
nunya Posted March 20, 2011 Share Posted March 20, 2011 My truck likes 87, it's the only number on the pump lower than his birth year 1 Link to comment Share on other sites More sharing options...
Tungsten Posted March 20, 2011 Share Posted March 20, 2011 A N/A VG, especially stock or close to stock, will benefit from 87 the most. A VQ will not, they need to be ran on premium, otherwise weird things will happen, like more carbon deposits, even when the computer re-adjusts the timing. The current gas system is retarded, I think 91 should be cheaper than 87. It's not how good the gas is, it's for what kind of compression it's made to run. Link to comment Share on other sites More sharing options...
BowTied Posted March 21, 2011 Share Posted March 21, 2011 OP: great post, thanks for taking the time to do it. We realize that you didn't intend to be wholly scientific, no worries. This is a real world test and it is useful for comparison sake and as a guideline. I appreciate that you ran some fuel in between tests to allow some computer learn time. I wonder how many tanks is required for that? If you ever decide to repeat the test (such as after a tune up) I suggest running a bottle of good fuel injector cleaner through a litle while before starting the test (5-6 tanks before maybe). I would also recommend that the next time start with the premium. If you have the time and patience (now I am asking a lot with this one): run at least 6 tanks of each to improve the average accuracy. If you are wanting to reach for the stars on this also do a set of midgrade tank tests (having had my doubts on the value vs economy vs performance thing myself I run midgrade all the time). I'd do the test myself but my wife gets to drive the pathy all the time Link to comment Share on other sites More sharing options...
piste Posted March 21, 2011 Share Posted March 21, 2011 what I can't reconcile is that for my '97 SE the owners manual recommends "AT LEAST 87" for octane. If there were no benefit to running a higher octaneWhy would they state it that way (instead of specifically recommending 87 and 87 alone)....? I believe I get slightly better performance with 93 octane...and I'm willing to pay the extra money to give up that 0.129 miles per dollar. A number of folks state that running premium can be a waste of money....I don't think it is for me...and in the end ...each of us are entitled to "waste" our money as we wish. Link to comment Share on other sites More sharing options...
adamzan Posted March 21, 2011 Share Posted March 21, 2011 I think they say at least because in some places (like parts of the us that I was in this summer) had 85 octane as regular. My pathy did not like that @!*% so I ran premium. Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 22, 2011 Share Posted March 22, 2011 A N/A VG, especially stock or close to stock, will benefit from 87 the most. A VQ will not, they need to be ran on premium, otherwise weird things will happen, like more carbon deposits, even when the computer re-adjusts the timing. The current gas system is retarded, I think 91 should be cheaper than 87. It's not how good the gas is, it's for what kind of compression it's made to run. ^This. But it's a money grab for the oil companies. Which is why this won't change any time soon. Link to comment Share on other sites More sharing options...
Tungsten Posted March 22, 2011 Share Posted March 22, 2011 I find that my pathy (vg30e) likes somewhere between 87 and 89 octane fuel. Link to comment Share on other sites More sharing options...
Kingman Posted March 22, 2011 Share Posted March 22, 2011 I ran a tank of premium fuel through my '87 Z31T. Gas mileage was dismal, somewhere around 17MPG. Sad thing is, when I turn up the boost I'll have to run premium. Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 22, 2011 Share Posted March 22, 2011 I ran a tank of premium fuel through my '87 Z31T. Gas mileage was dismal, somewhere around 17MPG. Sad thing is, when I turn up the boost I'll have to run premium. Naturally. But your Z will love you for it. I was in the same boat when I got the 7... Premium isn't cheap. But for a huge-ass car, it gets great mileage. Back on-topic, though. I think it's fair to say the higher the compression of an engine, the more likely it is to run on higher octane fuel. Link to comment Share on other sites More sharing options...
Matt4949 Posted March 22, 2011 Author Share Posted March 22, 2011 Hey guys, Thanks for all the input in response. I feel I should clarify a little on my figures. Basically, my true-world mpg I would anticipate being a bit higher, considering numerous factors, but mainly my round figure of 18 gallons, being rounded up rather than down, decreasing my mileage. If the same figures were calculated using 17 gallons, they would look like this... Regular Fuel (87 Octane) 242.5 miles / 17 gallons = 14.268 mpg 254.1 miles / 17 gallons = 14.947 mpg 247.6 miles / 17 gallons = 14.565 mpg 256.9 miles / 17 gallons = 15.112 mpg Average: 14.723 miles per gallon Premium Fuel (93 Octane) 262.4 miles / 17 gallons = 15.435 mpg 261.6 miles / 17 gallons = 15.388 mpg 256.3 miles / 17 gallons = 15.076 mpg 260.7 miles / 17 gallons = 15.335 mpg 261.2 miles / 17 gallons = 15.365 mpg Average: 15.320 miles per gallon In all likelihood, running the tank dry (21 gallons) would get me over 300 miles on the premium fuel. Either way, the important figures to take from this post were the miles per dollar figures. This shows truly what value is held within each fuel type, regardless of anything else. Putting the mpg was really just another way to compare the fuels, in a figure everyone knows and recognizes. Back to my original point however, the statement "premium fuel recommended for maximum performance" appears on both my fuel door and in the manual. Let me tell you they are not kidding. While the knock sensor prevented any knocking with the 87 octane, it was clearly inferior in performance. Saving the $10 a week was just not worth it with how lazy the truck seemed to run. So it would seem to me by the knowledge imparted by these forums, that the VGs tend to run just fine with the regular fuel, while the VQs do not. BowTied, Appreciate your thoughts on the topic. I recorded 5 tanks before the miles per tank reached 260 and seemed to level out. Thanks for the suggestion, the injector cleaner will most certainly be part of this summer's tune up! Will let everybody know what kind of numbers I get after a little dirty fun under her hood! Link to comment Share on other sites More sharing options...
rgallant Posted March 22, 2011 Share Posted March 22, 2011 Just to add my 2 cents I have a 97 so a VG motor, and it seems a little peppier on higher octane 94 vs 87. Less sluggish at low rpms on hills. Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 23, 2011 Share Posted March 23, 2011 Really? I ran premium in my '98 a few times, and the difference was negligible at best. I found it ran its best on 89 (mid-grade in MB) fuel and a bottle of Lucas Injector additive every third/fourth fill. On my commute to work yesterday, I was able to squeeze nearly 300 miles out of 3/4 tank of Shell V-Power, for about 20MPG hwy. I was pretty happy with that. It would be nice to keep that kinda mileage with a SFD and bigger tires. Link to comment Share on other sites More sharing options...
02silverpathy Posted March 23, 2011 Share Posted March 23, 2011 $.02 The main problem with any figure here is the ridiculous blend of ethanol in the gas. You just never know what percent of TruE gasoline you are getting...we may assume as least amount of gasoline as possible. While I am all for making the earth green again, I can say that corn should be on my table not in my tank. I have only run 93 Shell V-Power in my rig....2 times since I bought it (w/42K now 78K)I ran 89 Shell and noticed only small "light on its feet" difference. After understanding how oil/fuel delicate the VQ is (and yes it IS painful to say delicate), I have run only the best in it...note I do not drive it everyday, it costs a lot compared to my oversized lawnmower Honda HB. What I can say is that by adding the CoRRecT amount of Toluene/Marvel Mystery Oil to your tank you can boost your Octane and get crazy response from your rig (VQ powered)and not damage anything. Yes let the naysayers join in, but before they do please google...Vette and Porsche owners mess with making their own racing fuels all the time. The VQ is no less of a racing engine than a 5.7 V8 Chevy....just smaller lol! Link to comment Share on other sites More sharing options...
Kingman Posted March 23, 2011 Share Posted March 23, 2011 Very good point about the ethanol content in fuels nowadays. I do my best to fill up at a gas station in town that sells pure, NON ethanol, fuel. Matt, do you have one of those around your area? If so maybe give that a shot. It's a little more spendy but I do think it is worth it. I consistently get 3-4 sometimes 5 MPG better with the pure fuel than any other fuel containing ethanol. Consistently. The engine also makes more power and runs more efficiently. Link to comment Share on other sites More sharing options...
Towncivilian Posted March 23, 2011 Share Posted March 23, 2011 (edited) This is a wonderful site documenting ethanol-free gas stations in the US. The one listed for my town contains ethanol, unless I was at the wrong station Edited March 23, 2011 by Towncivilian Link to comment Share on other sites More sharing options...
Matt4949 Posted March 23, 2011 Author Share Posted March 23, 2011 Unfortunatly, unless I'm mistaken, in the merry land of CT (where it's snowing 6 inches possibly today ) I'm pretty sure all gas, regardless of grade, contains "no more than 10% ethanol." Towncivilian, Thanks for that site. What a great resource! Now all I need to do is get out of this God forsaken state while I still can Link to comment Share on other sites More sharing options...
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