Better fuel economy after an oil change??

[RayCJ]

Originally Posted by Railrust
I've noticed this "phenomenon" now for quite some time right after an oil change, my truck gets better fuel economy right after an oil change (lasts for maybe a 1,000 miles). I'm talking an uptick of about 2 mpg for around 1,000 miles.

Just this past Monday I changed my oil and filter (0w20 Rottela Gas Truck 8 quarts 5.3 Chevy Silverado) and I've averaged between 27-28 on my daily 80 mile round trip commute. It's mostly highway and easy back road driving, but yesterday I was stuck in some traffic, did some idling and I thought...there's no way I'm going to average over 26 when I pull into that parking lot. And sure enough as I pull in the dash computer says 27 (and I realize the dash isn't accurate but it's what I go by).

I'm figuring new oil seals the rings better? Maybe new oil is just "clean" without the fuel dilution yet and contamination? And I'm not a Rotella Gas Truck advocate, I only use it because of the rebate...I mean it seems like good oil, but I experience this uptick in fuel economy with any oil, on any vehicle I've owned for the most part. Anyone else experience this?


FWIW, in all my older vehicles (1970's, 80's, 90's and early 2000) I noticed the same thing. Conventional oil in the early vehicles was typically changed at 3000 to 3500 miles and in the last 1000 miles you could hear and feel a difference in performance and you could measure it in MPGs. This continued right up to (and through) the 90's. In the 2000 timeframe, synthetics were starting to take off and OCIs were getting pushed to 5000 miles. I could start to notice more noise and rougher idle when the oil got to 4000 miles. I can't say for sure but I would agree that the last 1000 miles of that oil, I would notice a drop in economy -possibly a couple MPG but I can't say exactly. With my 2007 and 2009 Mazda 6's, 2011 Tacoma and my 2018 Mazda3, I run the oil 5-6k miles and I no longer notice any appreciable difference nearing the OCI. Maybe if I pushed the oil to 7.5k, I might notice a difference toward the end. I choose to do 5-6k OCI's so I'll never know. Honestly, I think oil and engine quality have reached a refined state where you'd have to be borderline abusive before you feel a difference.

 

[bbhero]

Originally Posted by demarpaint
2 mpg is a big increase. I typically air my tires up when doing an oil change if they need air. Are you airing up your tires too?



Actually I have seen a 1-1.2 mpg increase in fuel economy after changing the oil in my Ford Fusion and then my Nissan Altima VQ... I have recorded this over 50 times... After 2500 all the way up to 3500 miles this increase was noticed and observed. Interesting note... Pennzoil Ultra and Castrol Extended Performance gold bottle both maintained best fuel economy the longest.
These fuel test runs were all done on the exact same area on Rte 5 west of my area.... On a place where that road is dead straight for 2.8 miles...

Only one time there was a big variance... 27.4 heading west on Rte 5 into a strong northwest wind of 15 mph with gust up to 30... And 31.6 headed east bound on Rte 5 the opposite way.

Talk about having the proverbial winds at your sails

 

[Railrust]

Originally Posted by RayCJ
Originally Posted by Railrust
I've noticed this "phenomenon" now for quite some time right after an oil change, my truck gets better fuel economy right after an oil change (lasts for maybe a 1,000 miles). I'm talking an uptick of about 2 mpg for around 1,000 miles.

Just this past Monday I changed my oil and filter (0w20 Rottela Gas Truck 8 quarts 5.3 Chevy Silverado) and I've averaged between 27-28 on my daily 80 mile round trip commute. It's mostly highway and easy back road driving, but yesterday I was stuck in some traffic, did some idling and I thought...there's no way I'm going to average over 26 when I pull into that parking lot. And sure enough as I pull in the dash computer says 27 (and I realize the dash isn't accurate but it's what I go by).

I'm figuring new oil seals the rings better? Maybe new oil is just "clean" without the fuel dilution yet and contamination? And I'm not a Rotella Gas Truck advocate, I only use it because of the rebate...I mean it seems like good oil, but I experience this uptick in fuel economy with any oil, on any vehicle I've owned for the most part. Anyone else experience this?


FWIW, in all my older vehicles (1970's, 80's, 90's and early 2000) I noticed the same thing. Conventional oil in the early vehicles was typically changed at 3000 to 3500 miles and in the last 1000 miles you could hear and feel a difference in performance and you could measure it in MPGs. This continued right up to (and through) the 90's. In the 2000 timeframe, synthetics were starting to take off and OCIs were getting pushed to 5000 miles. I could start to notice more noise and rougher idle when the oil got to 4000 miles. I can't say for sure but I would agree that the last 1000 miles of that oil, I would notice a drop in economy -possibly a couple MPG but I can't say exactly. With my 2007 and 2009 Mazda 6's, 2011 Tacoma and my 2018 Mazda3, I run the oil 5-6k miles and I no longer notice any appreciable difference nearing the OCI. Maybe if I pushed the oil to 7.5k, I might notice a difference toward the end. I choose to do 5-6k OCI's so I'll never know. Honestly, I think oil and engine quality have reached a refined state where you'd have to be borderline abusive before you feel a difference.



With me, regarding the oil change thing/gas mileage, it doesn't last long. This is like a 500-1000 mile thing (if that), then it settles. It's noticeable to me because I drive this vehicle everyday...500 miles a week...same commute everyday...26,000 miles a year. I keep an eye on fuel economy - generally if the temps are above 40 I average 26-26.5 when I pull into work. After this oil change I was pulling in and it was 28.9 (day 1), 27.7 (day 2), 27.2 (day 3)...etc. That's pretty good for a full sized V8 4x4 truck, with some traffic at 7 am and again at 4 pm. Better than what I usually get.

Now I have noticed things with oil/OCI....usually when my oil reaches a certain point (4,000 miles with my previous car Lexus LS460) I'd start using oil. I wouldn't be using a drop UNTIL I reached 4,000 miles - then I'd use a quart and a half between 4,000 miles till 7,500 miles. I eventually decided to change the oil at 5,000 miles instead of extending it to 7,500. With my truck I don't use any oil until it reaches 2,500 miles, then I'll use 3/4 a quart until 5,000 miles. Both engines were direct injected, however the Lexus was port injected and direct injected (both engines had timing chains, with the Lexus having a HUGE timing chain). I always use a "high quality" name brand Synthetic (Mobil 1, Pennzoil, Valvoline, Castrol), whatever is on sale. But I do notice that the oil starts to "act" a little different at certain mileage points...usage, engine noise, fuel economy, etc.

 

[demarpaint]

Originally Posted by bbhero
Originally Posted by demarpaint
2 mpg is a big increase. I typically air my tires up when doing an oil change if they need air. Are you airing up your tires too?



Actually I have seen a 1-1.2 mpg increase in fuel economy after changing the oil in my Ford Fusion and then my Nissan Altima VQ... I have recorded this over 50 times... After 2500 all the way up to 3500 miles this increase was noticed and observed. Interesting note... Pennzoil Ultra and Castrol Extended Performance gold bottle both maintained best fuel economy the longest.
These fuel test runs were all done on the exact same area on Rte 5 west of my area.... On a place where that road is dead straight for 2.8 miles...

Only one time there was a big variance... 27.4 heading west on Rte 5 into a strong northwest wind of 15 mph with gust up to 30... And 31.6 headed east bound on Rte 5 the opposite way.

Talk about having the proverbial winds at your sails

I stopped frequently checking mpg years ago. An old E-150, a Jeep Wrangler, and Liberty are not exactly economy cars. When I did check mpg, the biggest gains were from airing up tires, or on a long road trip. I'm not disputing what you're saying, I was never that fortunate.

Not to split hairs, the OP noted a 2 mpg increase, which is nearly double the increase you saw. Either way that's great. I'll start paying closer attention, if I remember a few tankfuls before and after an oil change.

 

[bbhero]

Originally Posted by demarpaint
Originally Posted by bbhero
Originally Posted by demarpaint
2 mpg is a big increase. I typically air my tires up when doing an oil change if they need air. Are you airing up your tires too?



Actually I have seen a 1-1.2 mpg increase in fuel economy after changing the oil in my Ford Fusion and then my Nissan Altima VQ... I have recorded this over 50 times... After 2500 all the way up to 3500 miles this increase was noticed and observed. Interesting note... Pennzoil Ultra and Castrol Extended Performance gold bottle both maintained best fuel economy the longest.
These fuel test runs were all done on the exact same area on Rte 5 west of my area.... On a place where that road is dead straight for 2.8 miles...

Only one time there was a big variance... 27.4 heading west on Rte 5 into a strong northwest wind of 15 mph with gust up to 30... And 31.6 headed east bound on Rte 5 the opposite way.

Talk about having the proverbial winds at your sails

I stopped frequently checking mpg years ago. An old E-150, a Jeep Wrangler, and Liberty are not exactly economy cars. When I did check mpg, the biggest gains were from airing up tires, or on a long road trip. I'm not disputing what you're saying, I was never that fortunate.

Not to split hairs, the OP noted a 2 mpg increase, which is nearly double the increase you saw. Either way that's great. I'll start paying closer attention, if I remember a few tankfuls before and after an oil change.



Yeah it is all good...

The fact is was so repeatable was very interesting. And the observation that Pennzoil Ultra and Castrol Extended Performance gold bottle maintained better gas mileage the longest was very interesting to note... Everytime I ran either of those oils. .

Valvoline full synthetic started dropping field mileage after 2500 miles.. has did Havoline Pro DS... And Mobil Super synthetic.