My other car cannot handle anything under 93 octane. Every car has it's own ability to dial in timing to handle different gas. Knock sensors allow timing to be retarded or advanced depending on the octane. More timing advance gives greater power but will cause knock or pre detonation if the octane is not high enough (octane is a measure of resistence to pre-ignition). If the car has to retard timing due to knock/low octane then you get worse performance and mileage. The question is whether the cost differential in octanes is overcome by the mileage savings?

I've never noticed a measurable difference in mpg running regular. As mentioned I can feel the performance difference though. I pull a lot of long hills and will get a little detonation if lugging up the hill on 87 octane so that's another reason I usually stick to the 89+. I have found some 87 octane fuels that don't detonate though, but they still don't perform as well. According to the book, "premium" is 91 octane but we only have 87, 89, and 93 around here.

Things I have done to maximize MPG and my experiences:

Use of synthetic oil (especially important in cold climates).

Use of MotorKote oil additive. It’s an oil hyper lubricant that truckers swear by. If it makes my chain saw run cooler, hey, it’s got to help my PF, too. (Company based in Columbus OH area).

Tires at 40# front, 45# rear (some tires may tend to hop sideways on rough roads). Some tires have less rolling resistance (I’ve been told that Michelin is in that group. Others now have LRR tires) Oversize tires hurt MPG. “Passenger” tires roll better than the Light Truck (LT) models.

VOLO Performance Model FS3. I get an 8-10% improvement. ($90. It gets wired into the OBD II wiring. An email response from the company explains: “The chip reads the ECU and only the ECU's calculated fuel delivery and timing values are altered.”

Drilled a few extra holes in the air filter box

Prem fuel does not help me with local driving. I feel it is slightly worth it on a trip.

Get a Scan Gauge & look at your instant MPG. Plugs into the OBD2. Teaches you to go light on the pedal. If you sign up at the http://www.cleanmpg.com/ forum you can get one for $135. That forum instructs you how to get the most MPG possible by training the person behind the wheel. An Ultra Gauge is cheaper but has fewer gauge options.

Drive slower. I get ~21 doing 65 on interstate. For a comparison, drove 50-55 on a 4 lane state road with little traffic and got 26.2 each direction of a 160 mile trip (80 miles x 2)

Winter fuel sucks.

Get up to 40MPH as soon as practical for the trans torq converter to go into lock-up (5th gear) Slush-a-matic till then. Wish the PF had the manual option like the Xterra. Of course, other parts of the world have the MT & diesel options, but not North America. Sad.

When i'm doing alot of highway driving i usually average around 14l/100k, but thats only after say, a long road trip (8+ hours) but then again most of my trips end up going over the rockies and to be honest i run my vehicles pretty hard up some of those hills on the coquihalla

What size are those BFG's? Even in stock size those babies will cost you a solid 1mpg, maybe more on the highway.

Hey! Thought I'd chime in on this.

Was your gas mileage as bad during the warmer months? I live in North Dakota and my truck sits outside now (girl friend, sometimes not worth it), and the choke runs pretty much all the way to work. That's about 15 miles. I've tried plugging it in (oil pan heater) and I seem to do a little better. I get about 13.5 mpg in town.

Is your truck sitting outside? How much time do you let it warm up/idle? How much stop and go, my commute consists of about 60% cruise set at 60 mph. Stop and go will hurt you a lot more. Hope maybe this will help.

Oh, and for all of you cold weather pathy people. Does anyone have an engine block heater? Wondering if this would help with the choke run less time.

Thanks
~Alex

While it doesn't really have a choke, it does run with higher fuel burn during cold-loop cycle. I've noticed it's very high with the Pathfinder...but don't recall the numbers. I'll hook my scanguage up and take a look. It's not horribley cold here but regardless, the cold-loop burn will be similar it will just run in that mode longer the colder it is.

As for oil heater..it would help a little but a coolant heater would do the best. That's what trips the engine temps and adjusts the injection qty.

Thanks for all the tips guys, i think i'm going to start plugging it in even though it's only around -2 here on the colder days, and +2 on the warmer ones. perhaps that will make it run at less RMPS on ignition

valenburg wrote:check your driveline (u joints) I was getting pretty low mileage and my forward shaft joints were DONE. Replacing them got me another 1-2mpg. Perhaps maybe your fan is stuck on.

What do you mean "maybe your fan is stuck on"? I though ours was a clutch fan and attached to a pulley, therefore always on

The cooling fan clutches are know to fail from time to time. Mine went at 90k. You'll notice your Pathy sounds like a dumptruck even when accellerating slowly from a stop... you'd definately feel a little down on power if it failed.

Fofiddy wrote:The cooling fan clutches are know to fail from time to time. Mine went at 90k. You'll notice your Pathy sounds like a dumptruck even when accellerating slowly from a stop... you'd definately feel a little down on power if it failed.

I understand what your saying. My neighbors 2009 sounds like that and i always wondered why.

Skinny, do know of an inline coolant warmer/heater that you would recommend? I live in the midwest, and my wife maybe drives 2-3 miles to work. The Pathfinder never gets warmed up and she is averaging about 10 mpg as well. Not to mention, it is very hard on an engine when it is always running cold and never has a chance to warm up. I'm not so much worried about the mpgs at this time, but taking care of the engine.

Moto wrote:Skinny, do know of an inline coolant warmer/heater that you would recommend? I live in the midwest, and my wife maybe drives 2-3 miles to work. The Pathfinder never gets warmed up and she is averaging about 10 mpg as well. Not to mention, it is very hard on an engine when it is always running cold and never has a chance to warm up. I'm not so much worried about the mpgs at this time, but taking care of the engine.

Could she go out 10 minutes early and start it? seems simpler and cheaper then a inline warmer

dared3vil00 wrote:

Moto wrote:Skinny, do know of an inline coolant warmer/heater that you would recommend? I live in the midwest, and my wife maybe drives 2-3 miles to work. The Pathfinder never gets warmed up and she is averaging about 10 mpg as well. Not to mention, it is very hard on an engine when it is always running cold and never has a chance to warm up. I'm not so much worried about the mpgs at this time, but taking care of the engine.

Could she go out 10 minutes early and start it? seems simpler and cheaper then a inline warmer

Could she? Yes. Will she? No.

Moto wrote:Skinny, do know of an inline coolant warmer/heater that you would recommend? I live in the midwest, and my wife maybe drives 2-3 miles to work. The Pathfinder never gets warmed up and she is averaging about 10 mpg as well. Not to mention, it is very hard on an engine when it is always running cold and never has a chance to warm up. I'm not so much worried about the mpgs at this time, but taking care of the engine.

I used to have one on my diesel VW Jetta. It was a kit a guy put together with the perfect hoses and such, but the heater itself was a Zerostart. Given the amount of fuel used during cold start...idling to warm up is the worst option from an efficiency standpoint. Idling is the slowest way to warm up an engine. The other upside to the coolant heater is you'll have instant heat for the cabin as well, something the oil heater doesn't provide.

Of course if your wife won't go start car...will she remember to plug it in/unplug it in the morning? I would never put one on my wifes car because she would drive off with the extension cord for sure.

How about a remote start and suck up the fuel?