Subaru Forester Owners Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
42 Posts
Discussion Starter #1 (Edited)
Alright, so about a month ago I picked up a 2010 N/A 5 speed Forester. I moved into it, checked all the fluids, washed it, basically made it mine. However, when it came time to double check the tires were inflated properly, for some odd reason I just trusted the dealer. Don't know why, but that's what happened.

I've driven about 1250 miles in this thing, and the city mileage has gradually been getting worse and worse. When I first bought the thing, city mileage was around 21 mpg, then I did some highway driving, slowly it got down to 18.5 mpg, then this tank is down to 17.4 mpg (thus far, after about 70 miles).

Something wasn't right; I started altering my driving style figuring maybe it was me. Then I decided maybe I should check the tires, perhaps one was low. As I am in college, I went down to the local auto parts store and bought a tire pressure gauge (usually I borrow dad's when I'm at home), check the driver's side...30 in the rear, 32 up front. Good, just what the manual recommends. Jump over to the passenger side, the front had 40 psi and the rear had like 37 psi :icon_eek:

I mean *** who does that. Clearly the dealer filled it wrong (or the past dealer did...dealer trade). I started pooping bricks, because I recall seeing in the manual that it's bad to have the tires slightly different than they should be, but holy crap.

Being engineering students, I started discussing with my roommate possible consequences of this disaster, and he made a good point that it's possible all 4 were filled to ~40psi, until the driver's side tires slowly lost pressure, leaving me with an over-inflated passenger side, which makes some sense regarding the poor mileage.

Hopefully the mileage gets better after this (it rides MUCH smoother and handles better now...go figure lol), but I've got two questions:

1. Could this have been a reason for such poor mileage?
2. Did this hurt my drivetrain at all??? (I hope not...I'm kinda planning on keeping this car a loooooong time).

Gracias for the help

An aside: I suppose I also switched from 76 to Shell gas about halfway into this month of ownership. My buddy who is a biochemistry major said Shell has upped the Nitrogen content in their fuel, and he said that's useless because Nitrogen doesn't burn (or burn well, I forget). Either way, he said Shell is pretty ****ty gas, chemically speaking. Perhaps that's the cause?
 

·
Registered
2003 Subaru Forester XS
Joined
·
167 Posts
I don't think u could have caused any damage to the drive train, cause i dont think the 2010 has LSD . . . And, about the poor MPG - Shell does the same to my car :( , plus yours has very low miles on the clock, Yes? Once you hit around 7000 - 8000miles u'll see improvement .
 

·
Registered
Joined
·
42 Posts
Discussion Starter #4
Oohhhhh that makes sense if that part of the manual applied to a LSD. Either way I'm gonna go back and read through it and find that part again. Thanks for the help, and hopefully this was just a cause of Shell gas. I'll update after trying a different brand!
 

·
Premium Member
2017 VW Golf SportWagen 5MT
Joined
·
10,887 Posts
Were they 40psi hot or cold?

Either way, dealers are morons when it comes to tire pressure, same as most shops. I doubt they were evenly-filled at first and then driver-side lost air -- they were filled wrong to begin with. I wouldn't worry about it at all, just drop them down to around 33 front / 31 rear (measured cold) and have fun.

Stan
 

·
Premium Member
2013 Kia Rio Automatic
Joined
·
1,639 Posts
Ostrich, I am wondering what part of earth you are from? Reason I ask is I remember my Foz used to lose about 3 MPG with the combination of the winter mix of fuel as well as the colder temps in the winter. Of course if you are in like Miami, disregard...

PS. I found this out the hard way. I ran out of fuel! hehehe, and had to walk 2 miles, up hill in the winter time, in six feet of snow, barefoot (okay I am exaggerating a little here)....to get fuel because of the difference in MPG during my first winter.
 

·
Registered
2004 Forester XT
Joined
·
180 Posts
Did you get a dial gauge or a pen gauge? Most pen style gauges aren't the most accurate, a good dial gauge that holds peak pressure until released is the way to go. And I have to concur with the fact that most dealers/quickie lube shops aren't the most detail oriented for tire pressure.

As for possible damage, it's highly unlikely with that few miles. The gas mileage is probably due to winter fuel blends/weather and it being a new motor. Give it another 5 to 10 thousand miles before you can really start to see accurate MPG's.
 

·
Registered
2010 Forester
Joined
·
121 Posts
My dealer keeps putting 45 psi in our tires. Porbably won't be our dealer for service much longer. The theory is that it keeps the TPMS system from ever bothering them with low tire pressure alerts. Our 2010 does not drive well with that much air in the tires, feels like it is on tip toes. Can't be much use for tire wear, either.
 
1 - 8 of 8 Posts
Top