Increased Fuel Economy, Am I Crazy?

[LittleBittyBigJohn]

I've had my truck for several months now and have put 15,000 or so miles on it. I got it with around 25,000 miles and am up to about 42,000 now. The whole time I've had it I've gotten around 16.5 MPG empty and around 12.5 on an average hauling trip. I had the dealership change the oil until it got out of the 36,000 mile warranty and I did my own at around the 40,000 mark. Immediately after changing the oil my unloaded average is up to a little over 19mpg and my haul has bumped up to a little over 15mpg. I took an unloaded trip with my wife that was about 600 total miles and we got almost 22mpg. Seems rather odd to me? I used Rotella T6 and an Autozone K&N filter. The immediate change makes me think the oil caused better fuel economy but I have never heard of that before. What say you?

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[dodge man]

I doubt an oil change had an effect. It doesn’t take much to bump up the fuel mileage. If you get lucky and catch a tailwind in both directions, the AC runs a lot less, you drive a little slower etc.

I’d do some reading on K&N air filters if I were you. They generally aren’t that great. They don’t really increase performance and don’t filter as good as an old fashioned paper filter.

 

[LittleBittyBigJohn]

It's a K&N oil filter, not air filter. I know about the air filters. I had not researched the oil filters and needed a change so I just got what the guy at the counter suggested.

 

[dodge man]

I suspect their oil filters are just fine.

 

[ArlyA]

I'd guess some condition was changed you are overlooking. The Oil an filter is not the answer.

 

[LittleBittyBigJohn]

I'd guess some condition was changed you are overlooking. The Oil an filter is not the answer.

I don't doubt you at all. I am just at a loss of what it could be.

 

[jonsstihl]

could be if the dealer used 15w40 instead of 0w20. depends what your truck calls for but I agree it is unlikely that the oil is the issue. on my car the wind and speed driven affects mileage the most and ambient temps. as soon as it drops below freezing mileage drops even on long trips regardless of how slow I drive. and for some reason when it is raining seems to drop mileage even if there is no extra wind.

 

[George2615]

Getting that mileage is about right for your diesel truck. The longer the trip, the better the mileage. Short trips around town you'll be back down around 16-17. Be thankful its not a gas truck. I'm lucky to get 15 with my 6.0L (usually 13-13.5 avg.) but I don't take long trips. 90% of my trips are around town.

 

[dodge man]

I’m not a gas mileage freak but out of something to do I track it on longer trip. I hated the 55 mph speed limit when it was a thing but it does make a big difference on fuel mileage. It’s also something you can control. Driving 65 mph vs 75 mph makes a difference. I drive a little over the speed limit but driving on a 2 lane road you are usually driving slower.

Tailwind will really boost your mileage. If you have a 15 mph tailwind and are driving 75 mph your vehicle thinks it going 60 mph as far a wind resistance and fuel mileage.

 

[dieselscout80]

I think your diesel is getting broken in and that’s the increase in MPGs.