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Gas mileage


ahardb0dy
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Well my wife filled the pathfinder a few minutes ago so I'll get to see what kind of MPG I am getting with it next time i fill it ( probably by Friday the way this truck sucks down gas !),

 

The gauge was just below the 1/4 mark when I got home and it took 13.6 gallons, she said she couldn't get any more in. She was questioning the fuel gauge not going all the way to full but after I shook the truck for a few seconds the pointer is right on top of the white full line so I guess it's full.

 

I think I'm going to replace the cap and rotor and plug wires Saturday ( already have the parts, I've never replaced these parts since I had the JDM engine put in so no idea how many miles are on them. Also will pick up a air filter, O2 sensor was replaced already a while back. I want everything good that effects mileage so I can see if there is any difference. Guess I should really wait until I fill it again so I can compare.

 

I'll see, just can't stand that today I drove 32 miles home, RPM's below 3000 mostly around 2500 rpm and the gas gauge went from just under half to just below a quarter !!

 

 

 

 

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I feel you there. I'm currently getting on average 11mpg. What's odd is that I've very recently replaced plugs, cap, rotor, wires, coil, air filter, greased the connections on the passenger side injectors and imo this truck is now running better than it ever has, yet with much worse mileage.

Could be because i'm using 4wd more, warming it up more (between -5 and -30 all january long), but it's literally cut in half. I'd say about 50% of the time I let it run long enough to let the tranny fluid get warmed up to make shifting easier on my synchros but it's not like i"m letting it sit for a half hour at idle..

One thing that struck me was that I put 10w30 full syn in prior to a road trip in some extremely hot conditions last summer (115F in Moab, early July for example). I'm about due for an oil change and will be going w/ the typical 5w20 full syn, but could having such thick oil really bog the motor down that much? I mean once it's warm, it's warm. normal viscosity should return at proper operating temp, and I was consistently getting 15-19mpg on the freeway the entire road trip - over 1500 miles - with about 500# of gear in back, bikes on top, and two adults inside.

I have not replaced the o2 sensor since I bought the truck, and it's completely rusted in place so i need a new bung etc. but it throws no codes, doesn't stumble, doesn't seem to run rich or thin, etc.. Just gets 11mpg consistently.

 

Could my wheel bearings need grease? Could I be getting undue rolling resistance from something in the drive train by not fully unlocking the front hubs switching from 4wd in snow to 2wd on the freeway at stops/on the fly?

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I never have gone 4 wheeling in my truck and it smells like it runs rich, no codes, it has the JDM engine but it should be the same as a US engine as far as I know. thought maybe the injectors were bigger but no idea.

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One thing that struck me was that I put 10w30 full syn in prior to a road trip in some extremely hot conditions last summer (115F in Moab, early July for example). I'm about due for an oil change and will be going w/ the typical 5w20 full syn, but could having such thick oil really bog the motor down that much? I mean once it's warm, it's warm. normal viscosity should return at proper operating temp, and I was consistently getting 15-19mpg on the freeway the entire road trip - over 1500 miles - with about 500# of gear in back, bikes on top, and two adults inside.

No. It would not make a noticeable, measurable difference. 5W-20 is also not specified for our engines, use 5W-30 year round.

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Well my wife filled the pathfinder a few minutes ago so I'll get to see what kind of MPG I am getting with it next time i fill it ( probably by Friday the way this truck sucks down gas !),

 

The gauge was just below the 1/4 mark when I got home and it took 13.6 gallons, she said she couldn't get any more in. She was questioning the fuel gauge not going all the way to full but after I shook the truck for a few seconds the pointer is right on top of the white full line so I guess it's full.

 

I think I'm going to replace the cap and rotor and plug wires Saturday ( already have the parts, I've never replaced these parts since I had the JDM engine put in so no idea how many miles are on them. Also will pick up a air filter, O2 sensor was replaced already a while back. I want everything good that effects mileage so I can see if there is any difference. Guess I should really wait until I fill it again so I can compare.

 

I'll see, just can't stand that today I drove 32 miles home, RPM's below 3000 mostly around 2500 rpm and the gas gauge went from just under half to just below a quarter !!

You're running at at 3000RPM's? Yes you have a problem.

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once the snow comes I get about half the milage i do in summer. I chalk it up to thicker fluid in the diffs (i did switch to synthetic), the grease in the wheel bearings thickening. I know that happens on my bicycle, which is why i changed to lubra-plate ultra low temp grease. its rated from +50 to -50*c. not sure if I can use it in the trucks wheel bearings though. I'd sure like to find out because it made a HUGE difference on my bicycle.

The other thing is that in cold weather even the rolling resistance of your tires increases. engines don't run as well with ultra cold air. and I too use the 4x4 system all the time. I really like the shift on the fly system.

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I never have gone 4 wheeling in my truck and it smells like it runs rich, no codes, it has the JDM engine but it should be the same as a US engine as far as I know. thought maybe the injectors were bigger but no idea.

Hey buddy but did you just say that you have never gone 4-wheeling?

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used to go wheeling all the time in the hardbody back home, been 4 wheeling maybe 3 times since we moved to Florida and that was in the hardbody years ago,

 

I have proof,. LOL

 

10gmuli.jpg

 

2qlvr5u.jpg

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Should be running 5w30 in these rigs.

 

Well per the owners manual it says if the ambient outside temp anticipated before the next oil change is zero and above 10W30 or 10W40 is ok

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You still seem to be reving very high...what is your blood presure? Is your HB a 96? I still have a 96 in black,

Edited by kdj
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normal, I tend to drive fast in the morning as I am always rushing to make it to work on time, I try to leave the house on time but I have to drive 36 miles to get to work so if I leave 5-10 minutes behind I have to make the time up.

 

31's with 4.62 gears and the automatic, OD engaged that is where the truck runs doing 80-85, I don't do 80 the whole way, just in spots.

Edited by ahardb0dy
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No. It would not make a noticeable, measurable difference. 5W-20 is also not specified for our engines, use 5W-30 year round.

CostCo has some good deals on mobil1 right now, maybe I'll go pickup a couple cases so I have some on hand. Have a couple 5qt jugs of royal purple 5w20 I used in the bimmer and have run a few cycles through the pathfinder with no ill effects thus far..

 

I'm also running full synthetic in the diffs, would be curious to find some better cold weather bearing grease if in fact that's what's making the difference. Incidentally, if I get rolling and pull it out of gear, it doesn't feel like it's free coasting. Almost like a brake is stuck on slightly but they are not (fresh brake job, verified everything is moving freely etc.)

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Earlier 95 and before have low gearing so they rev pretty high at highway speeds. Always wanted a 6th gear if possible.

 

I was told by an Xterra guy that doing the knock sensor relocation can gain you a 1 or 2 mpg. I know these things are notorious for malfunctioning or incorrectly think there is a knock. Also, I'd strongly suggest looking into replacing the O2 sensor. It helped mine, it still smells rich but not as bad.

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She was questioning the fuel gauge not going all the way to full but after I shook the truck for a few seconds the pointer is right on top of the white full line so I guess it's full.

 

I drove 32 miles home, RPM's below 3000 mostly around 2500 rpm and the gas gauge went from just under half to just below a quarter !!

 

You obviously can't go by your gas gauge since the sender sticks or whatever, nor should you. The only way to determine mileage is by the math.

 

If you used 4-5 gallons to drive 32 miles, that would be 6.5-8mpg and that would mean you are leaving a trail of gas.

 

You're running at at 3000RPM's? Yes you have a problem.

Different animals. WD21s are geared lower due to less power and more wind resistance. Our R50 cruises 68mph @ 2,500rpm to get 18-20mpg depending on terrain. Our WD21, not so much...

 

B

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Well per the owners manual it says if the ambient outside temp anticipated before the next oil change is zero and above 10W30 or 10W40 is ok

10W-30 or 10W-40 is acceptable above 0F but there is no benefit over 5W-30 in the vast majority of cases.

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I plan on filling it again when I need too, than I can figure out the MPG, Today drove 72 miles, only went over 3K when accelerating up to speed and I was taking it easy, Gas gauge went from the full line to right around maybe just below the 3/4 line, gauge may not be working 100% but once I fill it again I will get an idea on the MPG.

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10W-30 or 10W-40 is acceptable above 0F but there is no benefit over 5W-30 in the vast majority of cases.

I've always been curious about this.. Did my research and it's now very clear. They are nearly identical at normal operating temperatures, so neither would have any impact on mileage at operating temperature.. They are the same thickness - 10 - @212F. It's the cold engine starts, and the high-temp, high-rev scenarios where the differences stand out and even at high temps the difference is often negligible, save for perhaps the race track. The engine oil weight recommended by the mfg is specific to the "thickness" of the oil at operating temperature, and it is this thickness measurement that determines the weight and grade required of the engine. The "cold" temperature does however impact overall stress at start due to the lower overall thickness of lower weight oils, and so extremely cold environments are better off using thinner weight oils to reduce startup wear.

 

Because 5w-30 and 10w-30 are nearly identical with regard to the operation of the engine at temp it's likely a wash unless you live where I do, in which case, thinner is better. Purely for the sake of being nice to these high mileage motors in the extreme cold at startup.

 

In cold weather however, oil thickness is much more significant. 5w-30 will be thinner, potentially significantly so. The colder things get the greater the difference between the two would be at cold start. 5w-30 thus providing more oil to the engine parts faster, requiring less work to flow across and through the internals and pumps, thus allowing for less wear and stress and a quicker, easier start. So in either situation - high temp high rpm driving, or extreme cold, thinner oil is better.

 

http://www.bobistheoilguy.com/motor-oil-101/

 

Chapters 3 and 5 talk about the differences at very low and very high temps but the whole thing is a great read. Especially the bit about storing oil in the cold..

Edited by madhakish
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I plan on filling it again when I need too, than I can figure out the MPG, Today drove 72 miles, only went over 3K when accelerating up to speed and I was taking it easy, Gas gauge went from the full line to right around maybe just below the 3/4 line, gauge may not be working 100% but once I fill it again I will get an idea on the MPG.

 

Mine, when driving conservatively on the highway will get about 140-170km to that point...City driving I get about 115 to each 1/4 roughly. Usually get 500 to about 65 liters of gas. Which works out to around 18 mpg. I can get low 20's on the highway in the summer. Winter is a write off dude to more idling and wheelspin haha.

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