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Late oil change resulting in lower mileage?

1K views 10 replies 9 participants last post by  spinlock 
#1 ·
I have an 08 JKU with 68k. I went on a road trip so lots of highway miles in a short time. I try to stay on top of oil changes but with the trip I ended up at about 5k between changes.
I noticed that shortly after the reminder came on my mileage dropped from 17-18 to 12-14. I thought it was due to the driving I was doing and the junk I was hauling around.
After getting the oil changed it is back to the usual 17-18. with the same type of driving and load. The oil level was never low and the oil was pretty clean looking and as I said it was a lot of highway miles.
It really seemed to drop fast when the reminder came on and jumped back up when it was reset.
Has anyone else noticed a decline in mileage when the reminder is on?
 
#3 ·
Well...you get really good mileage! I tend to average 15-17 on the highway. I would say that the drop in mpgs was probably more due to the roads/weather/what you're hauling. I drive 50-70 miles everyday, rarely have a load, but weather can make my mpgs drop into the 14s, or soar up to 19. Like I said, I average 15-17. I also go 10k between oil changes. However...I also run full-synthetic.
 
#4 ·
Oil change indicator, has nothing to do with your fuel mileage.......:thumb:

Plus 5,000 miles is not excessive for a oil change!!!!!!
 
#8 ·
I just wondered if anyone else noticed this.
I really didn't think the reminder coming on would have any thing to do with mileage but it was quite the coincidence that it dropped right when the reminder came on and went right back up when it was reset. I may try not resetting it at the next change just to see but if nobody else has noticed it it is likely just a coincidence.
The changing of gas blends may have been part of it.
I also suspect the fuzzy green thing that lives under the passenger seat may have had visiting family. Its aunt Sally could stand to go on a diet.
 
#9 ·
I also suspect the fuzzy green thing that lives under the passenger seat may have had visiting family. Its aunt Sally could stand to go on a diet.
I feel completely lost regarding this...
 
#11 ·
X2.

The ECU triggers the warning light. There is a possibility that the ECU is programmed to reduce performance after the oil has not been changed when an oil change is indicated in order to protect the engine. You wouldn't notice it in every day driving but when you are on the road adding miles continuously and monitoring gas mileage it becomes obvious.
 
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