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Premium Member
2014 Forester XT Touring CVT
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176 Posts
Discussion Starter · #1 ·
I purchased my Subaru Forester 2.0 XT Touring in the fall of 2013. The vehicle is a model year 2014.

Between 90,000 and 91,000 miles, the idle became rough and the engine seemed a bit noisier than usual. On a whim, or why not and let's see what happens I added some "Lucas Upper Cylinder Lubricant and Injector Cleaner" to a couple of tanks of gas. A couple means two, in case you were wondering.

After every oil change, I reset the lifetime MPG to zero, this gives me a good idea of how well the engine is running and how well I am doing at keeping my lead foot off the gas pedal and obeying the posted speed limits. Typically I am at the speed limit or within five miles of the speed limit. If you look at the picture posted below it shows three numbers calculated by the vehicle. The first number on the left is the lifetime MPG average calculated since my last oil change, 4,105 miles ago. The second number, in the middle, is the average MPG for the specific trip, this was coming home from work. The last number is the current oil temp, which is not really important for this discussion.

As of 10 July 2021, my current mileage is 91,860. Since using the "Lucas Upper Cylinder Lubricant and Injector Cleaner" the engine noise appears to have decreased the idle seems smoother and the MPG is very good in my opinion. In fact, the other day my trip average MPG briefly hit 35 MPG. In addition in the last week, my lifetime average MPG has increased by 0.2.

If you think the calculation done by the vehicle is overly optimistic then check my math from my most recent receipt.

I drove 243 miles I put in 8 gallons of gas. 243 / 8 = 30.38.

According to the vehicle calculation, my current lifetime average MPG is 28.5

The MPG for this specific trip was 30.8.

The majority of my driving is on the highway, I use the cruise control 99% of the time and my speed is between 55 and 60 MPH. Yes, there are days when I am the slowest moving vehicle on the road and yes I am always in the far right lane, the slow lane. I believe my moderate speed and constant use of cruise control are the two main reasons for such a good overall MPG.

Now, who believes the "Lucas Upper Cylinder Lubricant and Injector Cleaner" did anything to help?





555005
 

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Premium Member
2019 Crosstrek 2018 Forester XT
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14,789 Posts
I am guessing those numbers are a bit optimistic. The trip mpg on subarus are notoriously optimistic. 243 miles as a one time check is probably not reliable. I think you need 400+ miles on a round trip to balance elevation and then fill at the same gas pump. Around town my '18 gets about 22.5 with my wife driving. I do a couple mpg better. My best mileage on a trip was a calculated 30.5 at 450 miles.

If I were you I would consider using the CRC intake valve and turbo treatment. My '18 has 23K miles on it. I have done the treatment once and am planning on doing it again today. Good your vehicle is doing well!!
 

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2017 FXT Touring w/Eyesight
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33 Posts
I use it all the time in my 2008 VW R32 with 190K miles on it. Haven't yet tried it in the 2017 FXT Touring, but that's only got 16K on it (bought it 3 months ago with 15K on it). Thx for the info!

(BTW, we get around 26-28 mpg in the FXT with no special attention paid to maximizing it, but really no crazy acceleration either.)
 

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2017 Forester XT Touring EyeSight
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722 Posts
I've posted in lots of detail elsewhere, but I've calibrated both my '17 XT's odometer and my trip computer MPG against accurate references. The odometer is pessimistic with OEM tires, reading about 4.9 miles in 5 mile highway "speedometer check" test sections, and the trip computer is about +1 MPG optimistic compared to real gallons purchased over corrected odometer miles (many months, thousands of miles, so fill-up variation vanishes). Then, using these corrections and the free time I have being a retired engineer geek, I've run 15-mile constant speed MPG test loops on the same section of interstate (WA I-90 mp 34 to 42) far enough from my urban home to have light traffic that doesn't interfere with driving the entire loop at completely constant speeds 50 to 70 mph. Returning to the starting spot cancels out the effect of elevation and wind, and there is only one very brief stop sign at the far end of the loop, never with any traffic to wait for. The trend of MPG versus MPH is a very clear straight line, and my XT has always been in perfect running condition, today at 65,000 miles. It will get 36 mpg at constant 50 mph, 31 mpg at 60 mph, 26 mpg at 70 mph. So yes I believe your numbers - but no real trip I've ever taken, have I managed to average such slow speeds as you do.
 

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Premium Member
2014 Forester XT Touring CVT
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176 Posts
Discussion Starter · #5 ·
Here is some more gas mileage info in case anyone is interested.

The daily commute

Going in Coming home In case you are wondering the commute is 38 miles each way, 76 miles each day.
29.5 31.3
30.1 30.5
29.1 31.7
29.5 30.7
29.7 29.8

In addition, the average mileage since my last oil change has risen to 28.6. Which I think is pretty good for an all-wheel-drive vehicle.
 

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'14 Forester XT Touring
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756 Posts
Not bad. I average about 25 mph, cause I like to give it the beans on freeway on ramps.

My last road trip from California to Texas I did a best of 27-ish mpg. Yes I was going about 75-80 mph with the ac blasting on and full cargo with 4 adults. In August heat.

If I would have gone a tad bit slower I would have got the same mpg as yours.
 

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2012 Forester X Auto
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2,494 Posts
Not bad. I average about 25 mph, cause I like to give it the beans on freeway on ramps
...
If I would have gone a tad bit slower I would have got the same mpg as yours.
So you average 25mph and that's "giving it the beans"... :p
If you went a bit slower you wouldn't get a ticket in a school crosswalk zone!
:cool:
 

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'14 Forester XT Touring
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756 Posts
So you average 25mph and that's "giving it the beans"... :p
If you went a bit slower you wouldn't get a ticket in a school crosswalk zone!
:cool:
Haven't got one in over 10 years.....yet... (knock on wood)
fyi I work nights so....... unless the kiddies are out 1am maybe. LOL
Joking aside 85% of my driving is highway or rural back roads that are 50 mph.
 

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2012 Forester X Auto
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2,494 Posts
@Mr.AC
That's a good thing as Martha would say, but then they locked her up. ;)
My last encounter with the boys in blue was also a rural highway recently due to a radar indicated 78 in a 65...
Being courteous rather than argumentative and admitting my transgression might have helped because I just got a warning rather than a ticket.
I've since decided to be in a hurry less and enjoy life more...

As far as something actually thread related, I've noticed a couple things with the Foz that's probably applicable to both NA and turbos..
  • The mileage changes considerably with speed as mpg's go down as the needles go right.. Like @GMD observed, the Foz is capable of pretty good mpg's at lower highway speeds. My NA MY12 is lucky go get the low 20's at 80+mph, but I can get 35mpg keeping it under 55mph.
  • Stop and go and/or driving very slowly (low gears = high rpm for distance travelled) kills the fuel economy, and it will for any car that isn't electric.
Although you can't easily change local conditions unless you move, driving like you are always about to run out of gas can also make a BIG difference in the fuel economy you get.
 

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2014 2.5i Limited CVT
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2,776 Posts
Yes, the MPGs will change drastically based on driving conditions and what accessories you're using and if you've added anything (roof rack bars, cargo boxes or baskets, different wheels, tires, etc.).

Like @DragonSubie7 mentions, you get better mileage if you keep the RPMs down. I've been trying to keep the RPM under 3000 RPM regularly and notice bumps in the average MPG and how far I can go on a tank of gas. Almost all of my driving is on surface streets, little to no highway driving for me.

As I've added all of the "goodies" that kill mileage - all terrain tires, roof cargo basket, off-road lights, skid plates - I will usually see about 300 to 350 miles from a full tank. I also live in the desert southwest and so my AC is running at least 50 or 60% of the time. I also tend to be a bit heavy footed, trying to get up to speed as quickly as possible. And lots of traffic lights, cross traffic and idiots pulling right into traffic (slowly) as though my Forester is invisible....
 
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