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Gas Mileage went from 17's to 15's after Oil change
Posted: Sat Sep 10, 2011 4:15 pm
by conquerorhowie
I know it sounds crazy, but it's the truth. Right after changing my oil with Castrol GTX 5w30 and installing a Fram Tough Guard oil filter my gas mileage took a dip! My driving habits have not changed one bit! Has anyone ever experienced anything like this before?
From this
To this
Posted: Sat Sep 10, 2011 4:19 pm
by redwing
I changed my wipers and gained 2 MPG...Lol
Posted: Sat Sep 10, 2011 4:29 pm
by conquerorhowie
oh come on, be serious here.
Posted: Sun Sep 11, 2011 4:46 am
by res0ippr
I think you should feel good...its better than my 14 MPG and I'm running 0w-30 gas saver.
Do you do mostly highway? I think you should reset it and see what happens.
I also notice I tend to step on more with with fresh oil...
Posted: Sun Sep 11, 2011 5:23 am
by JAHBLESSINGS
It's the radio station. The music we listen to can depict how we drive.
Posted: Sun Sep 11, 2011 5:50 am
by skinny2
It appears to be very hot where you live. Any chance it was substantially more humid after the oil change? Was this just the difference of one fill before and after? Rotate tires or anything else during the service? Same fuel?
Only time I see a swing is when it gets really humid or we get switched to winter fuel. I was doing some long highway driving last week and switched out to plain-jane regular unleaded. I averaged 20.5 for three days of mainly highway driving (at 75+mph). Pretty happy with that. I usually run premium on my typical commute because I pull a lot of hills and need to pass trucks on two-lane roads. Average 18.5 on regular trips.
Posted: Sun Sep 11, 2011 12:12 pm
by conquerorhowie
res0ippr wrote:I think you should feel good...its better than my 14 MPG and I'm running 0w-30 gas saver.
res0ippr - I don't feel good, because with the price of gas, I think these low MPG's are unacceptable.
Do you do mostly highway? I think you should reset it and see what happens.
It's abot 50/50. At the time of and once there after the oil change I did do a reset, but i'll do it again.
I also notice I tend to step on more with with fresh oil...
because of the drop in mpg, i've actually been going slower.
JAHBLESSINGS wrote:It's the radio station. The music we listen to can depict how we drive.
Good catch, but not it my case 
skinny2 wrote:It appears to be very hot where you live. Any chance it was substantially more humid after the oil change? Was this just the difference of one fill before and after? Rotate tires or anything else during the service? Same fuel?
skinny2 - South FL is very hot and humid this time of year. This is the second summer since i've had the truck and it was not like this last year. Yes, this was an instant issue. I pulled the truck in my drive way getting 17.2 mpg, changed the oil & filter, reset the settings and now i'm down to 15.7, and lower. 
No, I did not rotate tires this time around, but in April I did put on a set of Hankook ATM RF10 65R17 tires.
For the past month or so I have been buying fuel at this private owned service station; I've just switched back to Hess, so I'll reset and monitor it.
Only time I see a swing is when it gets really humid or we get switched to winter fuel. I was doing some long highway driving last week and switched out to plain-jane regular unleaded. I averaged 20.5 for three days of mainly highway driving (at 75+mph). Pretty happy with that. I usually run premium on my typical commute because I pull a lot of hills and need to pass trucks on two-lane roads. Average 18.5 on regular trips.
Those are MPG's I'd be happy with. I do no towing and have no hills to encounter with, so I run 87.
Posted: Sun Sep 11, 2011 11:28 pm
by Npath
Ever since I switched to Good Year Wrangler Territory's, similar to the Dura-tracs, my mileage has nosedived. Your mileage is better than mine, 20+ miles more, as I'm only getting 18L/100km.
Posted: Fri Sep 16, 2011 8:38 pm
by fat_frog
What oil / filter were you using before this change?
Posted: Fri Sep 16, 2011 8:53 pm
by disallow
Npath wrote:Ever since I switched to Good Year Wrangler Territory's, similar to the Dura-tracs, my mileage has nosedived. Your mileage is better than mine, 20+ miles more, as I'm only getting 18L/100km.
Dude you should do your Primary O2 sensors.
Posted: Wed Sep 21, 2011 7:06 am
by Npath
disallow wrote:Npath wrote:Ever since I switched to Good Year Wrangler Territory's, similar to the Dura-tracs, my mileage has nosedived. Your mileage is better than mine, 20+ miles more, as I'm only getting 18L/100km.
Dude you should do your Primary O2 sensors.
Been thinking about that lately...
Posted: Wed Sep 21, 2011 7:15 am
by Npath
Disallow... how easily accessable are the sensors and what size wrench did you use?
I'll assume it has 4 O2 sensors and you suggested changing the 2 that are closest to the engine?
Posted: Fri Sep 23, 2011 9:08 am
by disallow
Npath wrote:Disallow... how easily accessable are the sensors and what size wrench did you use?
I'll assume it has 4 O2 sensors and you suggested changing the 2 that are closest to the engine?
I did it by peeling back the plastic wheel liner. I have pretty big hands, so access was fun, I had some battle scars. I couldn't get the old one out without sacrificing the connector.
Passenger side was harder than the driver side.
And yes, the 2 sensors you want to replace are the ones on the front side of the catalytic converters.
t
Seems like I found my answer.... BAD GAS!!!
Posted: Tue Sep 27, 2011 4:18 am
by conquerorhowie
fat_frog wrote:What oil / filter were you using before this change?
Proline
So before I replaced any parts I decided to switch Gas Stations. For the previous month before my oil change, (in an attempt find the lowest price) I started buying fuel from a Gas Station called "Victory". So after about 1 full up and resetting my computer and driving to and from Miami, which is a about 130 miles round trip I'm back to my 17.2 - 17.4 average. So that goes to show that trying to save a few pennies can actually cost you more $$$ in the long run.
Thanks to everyone who tried to help me on this.
Peace,
CQ