According to the onboard computer in my 2006 GMC Sierra, my MPG has suddenly increased about 5% (1MPG). I drive the Sierra about 24 miles (one way) to work (mostly 55 mph rural two lane) and there have been no changes in the route or the way I drive. The increase seems to have begun a couple of weeks ago just after performing some minor maintenance. Therefore, I think it is probably related to the maintenance.
However, all I did was:
1) Run through 20 gal of Techron treated fuel before the oil change (I typically do one before an oil change).
2) Changed oil (same oil as before (5W30 Quaker State dino)
3) Different oil filter (Bosch this time vs Pure1 before)
4) Added about 2-3 oz of Auto RX (never done before)
5) Changed the front axle fluid from factory 80W90 to Mobil1 75W90.
The only other thing that might have changed somewhat (though it’s hard to be sure) is it seems we’ve had somewhat less wind lately. And I have seen wind affect the MPG on this vehicle in the past. During windy spring months, I can loose 1/2 MPG or so on average. And in the winter, the mileage will drop 1+ MPG (to about 18.3 MPG). However, the jump I’m referring to above is a sudden one occurring in the middle of summer. Driving to work (for over a year now), I’ve never averaged over 19.7 MPG in this vehicle. However, the computer now reads 20.4 and is steady to rising. In addition, I’ve noticed no difference in the engine’s running manners.
Let me provide just a little more info on the MPG “measurements”. All the measurements I’m referring to are according to the vehicle’s on-board computer. I’ve checked it several times, and it seems consistent, and reasonably accurate (though a little optimistic, “adding” perhaps 0.3 MPG consistently). When reset, the computer’s calculated MPG typically settles down to a steady value within about 2 days of my routine driving to work. I usually reset it every 2 to 3 weeks, and it’s been about two weeks since its last reset.
Given all the above, I’m thinking the sudden MPG increase must be due to the front axle fluid change. Does a 5% MPG increase seem like too much of an increase for that change? I’ve never seen a significant effect on MPG from a Techron treatment (on this or any other vehicle). And it certainly can’t be due to a different oil filter. Does a small maintenance dose of Auto RX typically increase MPG? (Perhaps I should also ask this question in the Oil Additives section).
However, all I did was:
1) Run through 20 gal of Techron treated fuel before the oil change (I typically do one before an oil change).
2) Changed oil (same oil as before (5W30 Quaker State dino)
3) Different oil filter (Bosch this time vs Pure1 before)
4) Added about 2-3 oz of Auto RX (never done before)
5) Changed the front axle fluid from factory 80W90 to Mobil1 75W90.
The only other thing that might have changed somewhat (though it’s hard to be sure) is it seems we’ve had somewhat less wind lately. And I have seen wind affect the MPG on this vehicle in the past. During windy spring months, I can loose 1/2 MPG or so on average. And in the winter, the mileage will drop 1+ MPG (to about 18.3 MPG). However, the jump I’m referring to above is a sudden one occurring in the middle of summer. Driving to work (for over a year now), I’ve never averaged over 19.7 MPG in this vehicle. However, the computer now reads 20.4 and is steady to rising. In addition, I’ve noticed no difference in the engine’s running manners.
Let me provide just a little more info on the MPG “measurements”. All the measurements I’m referring to are according to the vehicle’s on-board computer. I’ve checked it several times, and it seems consistent, and reasonably accurate (though a little optimistic, “adding” perhaps 0.3 MPG consistently). When reset, the computer’s calculated MPG typically settles down to a steady value within about 2 days of my routine driving to work. I usually reset it every 2 to 3 weeks, and it’s been about two weeks since its last reset.
Given all the above, I’m thinking the sudden MPG increase must be due to the front axle fluid change. Does a 5% MPG increase seem like too much of an increase for that change? I’ve never seen a significant effect on MPG from a Techron treatment (on this or any other vehicle). And it certainly can’t be due to a different oil filter. Does a small maintenance dose of Auto RX typically increase MPG? (Perhaps I should also ask this question in the Oil Additives section).