Currently getting 20mpg City .. 22mpg Highway with my 98 Maxima .. Would it make sense to update my 02 Sensors.... Would it significantly increase the gas mileage?

 

My family has had 5 96-98 maximas over the yrs & they all got 27-28mpg on open road cruising at 68-70mph & 20-22mpg city at high miles all with original 02 sensors & cat using castrol syn blend high mileage 10w-30 oil.
My current 98 max (no rust) just turned 70k original miles with lucky for me many yrs life left in it,just love the way these cars feel & drive.
Many things affect fuel mileage like driving habits,cond of trans,state of tune,plugs coils & cleanlyness of injectors,throttle body & plate,intake valves & combustion chambers,cat converter,air filter,timely oil & filter changes & more!

Your city mpg is where it should be with that car but your highway mpg is way low with can be combination of more aggresive driving habits and or overall cond of the car/motor etc too so try starting here.

Id start with running s couple tanks of fuel treated with concentrated version of techron at 1.50z per gal fuel .

Then after that id treat a tank of fuel with a good cat cleaner and both these cleaners can clean 02 sensors too.

Could also get some MAF cleaner & take 10 mins to clean that & install a new air filter if it dirty.

Now get out on the open road for a steady cruise mpg test at max of 68-70mph to see if you can hit a min of 25-26mpg
but better for that car would be 27-28mpg.

If you now get better mpg great,but if not then its time to start hitting all the items i mentioned above if you want to improve mpg.

good luck.....Scott

 

one kind of cat cleaner? also should i use this techtron .. if i am already using premium 93 octane gas each fill up?

 

93 octane Premium fuel doesnt have near as much cleaning capability vs concentrated chevron techron injector combustion chamber cleaner used at 1.5oz techron per each gal of fuel being treated in a full tank of fresh fuel.

On the cat cleaner,go into any autozone advanced auto napa etc and ask for a cat cleaner and you will find mult ones you can choose from & add approx 25% more of the mfg's rec dose per gal of fuel when using the cat cleaner too.

Dont go for cheapest injector & or cat cleaner because more often then not you get what you pay for so cheaper cleaning product = less or not effective at all.

Happy Motoring!

Scott

 

My highway gas mileage increased from 27 mpg to 33 mpg after I replaced my upstream oxy sensors.

 

I just did a 4 hour road rip cruising around 85 MPH in my 98 maxima and still get 22MPG .. and that is using premium fuel.

 

The fuel mileage I reported is based on 65 to 70 mph..
The air conditioner was one some of the time as well
My car is a 5 speed. I drive like an old man I guess.
I'm 68. I do like to have some fun though.

22 mpg at 85 seems decent. Especially if your car has automatic transmission.

 

I second the MAF cleaning.

 

Going after a single … maybe a couple of … potential contributors in order to notably improve fuel efficiency is, I think, a pathway to even greater frustration. Unless, of course, you’re experiencing an obvious failure of some sort.

There are many factors that go into addressing perceived low fuel mileage.

Don’t get me wrong, O2 sensors and MAF condition are some them, and they can be important, but if/when you complete these tasks and if things don’t change to your liking, keep in mind that there many other things to look at, including your own driving style and your attention to other aspects of your car’s condition and upkeep.

 

Turbobinks comment is right on.

Some of us drive aggressively, and have a lead foot.
Combine that with lack of maintenance and low tire pressures, one would expect bad gas mileage.

Others drive a well tuned car with proper tire pressures
more conservativly. They get much better mileage.

 

my mechanic put in 5w30 synthetic oil.. is that not correct for my 98 maxima gle? with low mileage

 

5 30. oil is ok..

 

Not that it has anything to do with mileage, but over the decades, I’ve found that my car (that resides in west-central FL) seems to like 10W30 conventional over anything in the synthetic lines and of other viscosities.

Overall engine noise and especially noise on startup are quite reduced using the conventional.