OfftourRoadie96 Posted March 25, 2009 Share Posted March 25, 2009 As I was filling my gas tank today, at a whopping $2.09/gal, I was wondering what kind of gas do the rest of you guys use? I've been using the cheapest as possible. Especially with the way the economy is. Should I be using a higher octane? What about additives or synthetics? Link to comment Share on other sites More sharing options...
colinnwn Posted March 25, 2009 Share Posted March 25, 2009 whopping $2.09/gal, I was wondering what kind of gas do the rest of you guys use? ... What about additives or synthetics? How quickly we forget. Personally I think gas should be $10/gal, but i remember paying $4.50 in Dallas not too long ago. I use 87 octane because my engine is out of warranty and runs fine on it. I haven't been able to detect a difference in mileage on higher octane. You should run the cheapest gas your engine doesn't knock on. You can test higher octane, because your engine might run a more advanced ignition curve that would result in better mileage. If you are paying 10 cents more on $2/gal gas, you need to get 5% better mileage to make the expense of higher octane worth it. I think fuel additives are expensive junk that at best don't do anything. Not sure what you mean by synthetic (unless you are talking about oil). I do run 0-30 Mobil 1 synthetic engine oil with 10k filter changes and 20k oil and filter changes. And I am eventually going to get the synthetic oil in the tranny, diffs, and TC. I might see a tiny improvement in fuel economy with this. Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 25, 2009 Share Posted March 25, 2009 The difference between 87 and 91 is only a nickel or so per litre where I live; therefore I just run 91. I'm at present running Castrol Syntec 5W30, changing every 5,000km (roughly six months based on how much mileage I've put on the ODO so far). I run full synthetic in the diffs and tranny and I'm getting the mileage one can expect from a 11-year old SUV with about 170,000km on it. Every third fill I run Lucas Injector Cleaner/Conditioner with Lucas Booster; not sure if it's helped but my truck runs without compromise all the time. I am planning a Sea Foam cleaning as soon as I can get outside. Hopefully that'll clean out the intake/combustion/exhaust systems and I'll see some mileage improvement. Link to comment Share on other sites More sharing options...
01silvapathy Posted March 25, 2009 Share Posted March 25, 2009 I usually use just 87 cause its cheap. But every now and then i put in super premium..it just makes it feel like it runs better, and also use it when i need to race someone Its how I roll Link to comment Share on other sites More sharing options...
fukkeneh240 Posted March 25, 2009 Share Posted March 25, 2009 How quickly we forget. Personally I think gas should be $10/gal, but i remember paying $4.50 in Dallas not too long ago. I use 87 octane because my engine is out of warranty and runs fine on it. I haven't been able to detect a difference in mileage on higher octane. You should run the cheapest gas your engine doesn't knock on. You can test higher octane, because your engine might run a more advanced ignition curve that would result in better mileage. If you are paying 10 cents more on $2/gal gas, you need to get 5% better mileage to make the expense of higher octane worth it. I think fuel additives are expensive junk that at best don't do anything. Not sure what you mean by synthetic (unless you are talking about oil). I do run 0-30 Mobil 1 synthetic engine oil with 10k filter changes and 20k oil and filter changes. And I am eventually going to get the synthetic oil in the tranny, diffs, and TC. I might see a tiny improvement in fuel economy with this. $1.009/litre in Vancouver right now.. so that is almost $4/gal in CAD... with conversion i would guess roughly $3.60 ish in USD. anyhoo, i just use 87 for my vg33. i think you vq guys "require" 91. 93 up here is about 11 to 15 cents more per litre. Link to comment Share on other sites More sharing options...
InfinQX4 Posted March 25, 2009 Share Posted March 25, 2009 I run premium 91 becuase it's close in price to regular. Ran regualr 87 for years with no problems. Now that prices aren't at $4+, the difference comes to a few dollars a tank. I like the performance increase with 91 so it's worth it to me. When prices go up again (and yes I said when), I'll might go back to regular. Link to comment Share on other sites More sharing options...
laxman0324 Posted March 25, 2009 Share Posted March 25, 2009 First let's clarify something, Nissan recommends 87 for the VG33 and 91 for the VQ35. I never ran more than 87 in the VG33 b/c it wasn't fast enough for me to care about the very minimal performance gain. In my VQ35, I use premium around town since it runs so much smoother. I do use regular on long highway trips b/c I have always found a slight mileage increase with regular on the highway. I was on benzworld with my ML320, and many many people on that forum do the same thing. I don't know if this is right but something about the regular takes less effort to burn while cruising so the engine doesn't work as hard with regular. However when driving aggressively with regular you get preignition and knocking, hence why I use premium around town. Link to comment Share on other sites More sharing options...
InfinQX4 Posted March 25, 2009 Share Posted March 25, 2009 I do use regular on long highway trips b/c I have always found a slight mileage increase with regular on the highway. Never heard that before - I'll have to give it a try. Link to comment Share on other sites More sharing options...
adamzan Posted March 25, 2009 Share Posted March 25, 2009 The difference between 87 and 91 is only a nickel or so per litre where I live; therefore I just run 91. I'm at present running Castrol Syntec 5W30, changing every 5,000km (roughly six months based on how much mileage I've put on the ODO so far). I run full synthetic in the diffs and tranny and I'm getting the mileage one can expect from a 11-year old SUV with about 170,000km on it. Every third fill I run Lucas Injector Cleaner/Conditioner with Lucas Booster; not sure if it's helped but my truck runs without compromise all the time. I'm driving a 14 year old suv, with regular tranny fluid that should probably be changed, synthetic oil, and I get better mileage than you . Running 91 in the vg is pointless. My dad does it in his r50, I see no point, he gets worse mileage than I do. I do put 89 in when I take it on a trip and it seems to be good with that. Link to comment Share on other sites More sharing options...
Kingman Posted March 25, 2009 Share Posted March 25, 2009 The VG30I or E is designed to run off of 87 octane gas, and none else. Link to comment Share on other sites More sharing options...
adamzan Posted March 25, 2009 Share Posted March 25, 2009 Also you will get crap mileage if you use ethanol gas. That stuff is horrible. Link to comment Share on other sites More sharing options...
Kingman Posted March 25, 2009 Share Posted March 25, 2009 Also you will get crap mileage if you use ethanol gas. That stuff is horrible. Also destructive over time. Link to comment Share on other sites More sharing options...
02silverpathy Posted March 25, 2009 Share Posted March 25, 2009 (edited) That stuff is horrible and destructive. Running high octane in a lower compression engine VG33e will just make it hotter in the combustion chamber. The difference in octanes is explodabillity vs. its ability to be compressed. Higher octanes can be compressed more before exploding, therfore burning more and popping less. More burn = more heat. The VQ has a compression ratio of 10.3:1 and the VG is 9.5:1 quite a large difference. I wouldn't use less than 89 in a VQ (never used less than 92 myself), and no more than 89 in a VG. This is probably why somone got better mileage out of the VG with 87. Cooler combustion chamber temps make the fuel more predictable for ignition timing. If you feel like running "good gas" through the engine, buy it from Shell or BP. These companies use good quality additives to help maintain a clean engine....BP is always crazy expensive, I stick with Shell personally. Edited March 25, 2009 by 02silverpathy Link to comment Share on other sites More sharing options...
XPLORx4 Posted March 25, 2009 Share Posted March 25, 2009 (edited) I run premium 91 becuase it's close in price to regular. Ran regualr 87 for years with no problems. Now that prices aren't at $4+, the difference comes to a few dollars a tank. I like the performance increase with 91 so it's worth it to me. When prices go up again (and yes I said when), I'll might go back to regular. That's an interesting perspective. I've always observed that 91 is about 20 cents more than 87 (up to 24 cents more when gas is $4+), no matter how much regular costs, so when gas prices are lower, premium is actually much more expensive. At $2.09 [87] and $2.29 [91], premium costs 9.5% more than regular. That's a pretty substantial increase in relative cost per tank. If regular is $4.09, and premium is $4.34, using premium costs only 5.8% more. So, relatively speaking, it's not as big a difference to use premium when gas prices are higher. It seems to me that the actual dollar difference is the nearly the same between 87 and 91, no matter how much regular costs. Besides, using 91 octane in engines designed to use 87 doesn't serve any purpose except to lighten your wallet faster, unless your engine is prone to knocking. Higher octane gas reduces the frequency of knocking. Using 87 octane in an engine designed for 91 can result in lower performance and fuel economy. The VG33 engine in my Pathy has been on a steady diet of 87 octane for as long as I've owned it. There were only 2 occasions when I used 91 octane, and both times I topped off a partially full tank in order to get rid of pinging. Edited March 25, 2009 by XPLORx4 Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 25, 2009 Share Posted March 25, 2009 First let's clarify something, Nissan recommends 87 for the VG33 and 91 for the VQ35. I never ran more than 87 in the VG33 b/c it wasn't fast enough for me to care about the very minimal performance gain. I don't know what Nissan employee gave you that information... I've noticed my truck runs smoother when I run 91. I'm going to give 89 a shot and see how that works. I'm driving a 14 year old suv, with regular tranny fluid that should probably be changed, synthetic oil, and I get better mileage than you . Running 91 in the vg is pointless. My dad does it in his r50, I see no point, he gets worse mileage than I do. I do put 89 in when I take it on a trip and it seems to be good with that. Yeah, let's not forget your WD21 is bone stock. So duh you'd get better mileage... I doubt it's that much better. Link to comment Share on other sites More sharing options...
laxman0324 Posted March 25, 2009 Share Posted March 25, 2009 I don't know what Nissan employee gave you that information... I've noticed my truck runs smoother when I run 91. I'm going to give 89 a shot and see how that works. Owner's manual? I don't understand what your contesting, but my VG33 ran much better switching from dino to synthetic oil than increasing octane, and there wasn't even a but dino difference, so I don't mess with it. Link to comment Share on other sites More sharing options...
laxman0324 Posted March 25, 2009 Share Posted March 25, 2009 Using 87 octane in an engine designed for 91 can result in lower performance and fuel economy. I definitely agree about performance, hence why I only use it when I am on a long cruising trip. I don't have concrete numbers for my pathfinder but I found (along with many others on benzworld) in my ML that highway mileage increased with the 87 octane. I have used 87 a couple of times in my pathfinder and it seemed to give about a 1mpg better result, however I haven't had a long enough highway trip to really tell. Link to comment Share on other sites More sharing options...
colinnwn Posted March 25, 2009 Share Posted March 25, 2009 Running high octane in a lower compression engine VG33e will just make it hotter in the combustion chamber. Nope The difference in octanes is explodabillity vs. its ability to be compressed. Higher octanes can be compressed more before exploding, therfore burning more and popping less. More burn = more heat. Not exactly. http://en.wikipedia.org/wiki/Octane_rating Octane represents the ability of a fuel to resist spontaneous ignition with increasing temps (in an engine this is caused by adiabatic heating during the compression stroke). But it doesn't have anything to do with the heat content of the fuel. I don't know how preignition affects the heat absorbed by the engine. On one hand preignition represents an incomplete burn of the fuel so heat absorbed by the engine could go down, along with power absorbed by the piston. On the other hand since the piston is able to absorb less power it could drive engine temps up. Heat absorbed then radiated out by the engine, and expelled out the tailpipe, represent energy not converted to engine power. I wouldn't use less than 89 in a VQ (never used less than 92 myself) I use 87 octane in my VQ 99% of the time. You shouldn't do it if you are still under warranty, or notice preignition. But it works fine for me at less than 1000' MSL, and in an area with almost no hills. Only on very hot days, when I get on it too much, in too high a gear, I notice the faintest pinging. Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 25, 2009 Share Posted March 25, 2009 Owner's manual? I don't understand what your contesting, but my VG33 ran much better switching from dino to synthetic oil than increasing octane, and there wasn't even a but dino difference, so I don't mess with it. I'm not contesting anything, save where you obtained that information. That's it... My rig's been running on full synthetic since the PO bought it back in '02 so I wouldn't know what difference the change made, if any. I'm only running 91 because my VG feels better than it did running 87. Just being pragmatic, I guess... Link to comment Share on other sites More sharing options...
90seven Posted March 25, 2009 Share Posted March 25, 2009 87 octane is fine. Try adding a can of RESTORE to your oil at oil changes. Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 25, 2009 Share Posted March 25, 2009 87 octane is fine. Try adding a can of RESTORE to your oil at oil changes. I don't know if that stuff's available up here but I had used some Kleen Flo oil change conditioner and it worked like a charm. I'm going to look for this Restore stuff you speak of. Link to comment Share on other sites More sharing options...
laxman0324 Posted March 25, 2009 Share Posted March 25, 2009 I'm not contesting anything, save where you obtained that information. That's it... My rig's been running on full synthetic since the PO bought it back in '02 so I wouldn't know what difference the change made, if any. I'm only running 91 because my VG feels better than it did running 87. Just being pragmatic, I guess... My owner's manual in the 01 has all the info on both the VG33 and the VQ35 (I have no clue why). Making the switch to synthetic in the VG made it so much smoother, the VQ didn't seem to make much of a difference (just peace of mind with the clogging issues, mine isn't burning yet and I plan to keep it that way). Also, I second the Restore motion, I used that in my Accord at 160k and my ML320 at 200k and it made both of them feel much smoother through the RPM range, I have only used the Lucas Oil Synthetic stabilizer in both R50's but I like that a lot too... Link to comment Share on other sites More sharing options...
Fukinitupagain Posted March 25, 2009 Share Posted March 25, 2009 I used to use 89 (for like 8 years) but since the price isn't that differnt right now I use 91. I notice that when I use 89 I have an odd knocking noise but when I use the 91 its not there. Any ideas guys on what this is (this was true of my old engine as well)? Link to comment Share on other sites More sharing options...
colinnwn Posted March 25, 2009 Share Posted March 25, 2009 I use 89 I have an odd knocking noise but when I use the 91 its not there. Any ideas guys on what this is You are having pre-ignition, and you want to stop it. Your engine is a VG, so it should be perfectly happy on 89 or even 87. If it happens regularly (not just when you occasionally jump on it at low engine speed), you have 2 choices. If 91 always fixes it, then use it. Or you can try to find the root cause. I noticed you are running 32 inch tires. The larger tire means there is more load on your engine unless you switched your differential ratio to make up for it. That could be a contributing factor. If you live in a high elevation, or especially hot area that would make it worse. If you have a manual and you tend to run the highest gear you can, without downshifting to accelerate, that could cause it. You could also have a bad knock sensor, or MAF sensor, or maybe clogged injectors. Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 25, 2009 Share Posted March 25, 2009 You are having pre-ignition, and you want to stop it. Your engine is a VG, so it should be perfectly happy on 89 or even 87. If it happens regularly (not just when you occasionally jump on it at low engine speed), you have 2 choices. If 91 always fixes it, then use it. Or you can try to find the root cause. I noticed you are running 32 inch tires. The larger tire means there is more load on your engine unless you switched your differential ratio to make up for it. That could be a contributing factor. If you live in a high elevation, or especially hot area that would make it worse. If you have a manual and you tend to run the highest gear you can, without downshifting to accelerate, that could cause it. You could also have a bad knock sensor, or MAF sensor, or maybe clogged injectors. Would there be a difference between 4.3's and 4.6's? Link to comment Share on other sites More sharing options...
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