Can I expect a MPG gain going from 5W40 to 10 W30

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Perhaps in a OTR vehicle that sees many miles at the same speeds, but your Powerstroke would see more of an MPG improvement with better control of your right foot than you will ever see in a viscosity change.
 
Originally Posted By: Chewie
Theoretical gain? Probably. Measurable gain? Doubtful.


This
 
Originally Posted By: Chewie
Theoretical gain? Probably. Measurable gain? Doubtful.


Definitely that!

if you short trip it maybe .25-.5mpg
normal driving .25mpg or less.


And if you use it like a truck you want 5w40 in there.
 
Originally Posted By: wemay
Originally Posted By: Chewie
Theoretical gain? Probably. Measurable gain? Doubtful.


This


Yes, that.
 
You are feeding a lot of horses and the oil is going to be very little difference to them. If on a 120hp vehicle yes. 300+ no. I can't get the AC to change mileage on my 2 diesels. Keep feeding it a good oil and look elsewhere to try and gain. 5-6k pound truck is hard to change mileage much
 
The base oil viscosity is likely thicker in the 10W30 than 5W40 resulting in a possible loss of fuel economy.
A synthetic 5W30 with HTHS of >3.5 may be your best bet for improved MPG.
 
The difference will be immeasurable in a single truck. For one thing, many 5w-40 oils shear down an SAE 30 anyway. Second, there are a lot of other variables that make fuel economy go up and down.

Driver, tires, and aerodynamics will have a much more noticeable impact on fuel economy.
 
Do you use it like a truck? Do you tow with it?
If Ford recommends a 5W-40 over a 10W-30 for severe use, then I'd think carefully before going with a 10W-30.
As almost everyone has noted and as you already know, the search for a meaningful improvement in fuel economy represents the triumph of hope over experience.
Is this truck markedly thirstier than your old Dodge?
I remember something you posted about the fuel economy of your old truck and it sounded pretty good.
 
It most certainly makes a difference in fuel economy. Just one so small you'll likely never notice. It will be there; you cannot avert the laws of physics and those pertaining to pumping losses. However, the variability of daily driving makes it essentially impossible to find the perceptible change in the economy via the vis change, for the average person. The small shift can be magnified by driving a LOT of miles, and/or operating a fleet. Otherwise you'll not be able to discern it.

And I, for one, have never seen any real data that proves that a thicker lube is NEEDED for "severe" service. A good HDEO is a good HDEO, and minor vis grade differences matter not in the overall wear characteristics of a piece of equipment. That, and Ford's near-schizophrenic lube recommendations leave me shaking my head nowadays.
 
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Due to daughter at home, my Forester is "in use" so I drive my pickup 60 miles each way to work. It was not my plan when I bought the truck. A year ago I was working from home. Being an IT contractor things change quickly. Now I drive to work 4x/week and WHF one day.

I would stick with Rotella T6, but the CJ4 version is not easy to find. So I may need to change oils.

I am getting about 20 mpg. I set the CC for 65mph and go.
 
The next oil change run some 10w-30 and do the math. It doesn't need 2 pages of opinions.
 
Originally Posted By: 2015_PSD
Perhaps in a OTR vehicle that sees many miles at the same speeds, but your Powerstroke would see more of an MPG improvement with better control of your right foot than you will ever see in a viscosity change.


This^^^^^^^^

Originally Posted By: Rand
And if you use it like a truck you want 5w40 in there.


For the past 10 years I've run 10w30 in my LBZ Duramax towing 10k pounds up and down Idaho's mountains without any issues. All OTR commercial rigs have been factory filled with 10w30 for a while so what do you mean by "use it like a truck"?
 
Originally Posted By: Donald
I am getting about 20 mpg. I set the CC for 65mph and go.
My best MPG to date was 23.2 from Houston to Dallas. I was running 5W-40 (Delo 400 LE), but I did not speed, took extra care to avoid jack rabbit starts, and nearly all of it was highway miles (Met Overkill for dinner and he saw the MPG). Now, do I think that xW-30 would have miraculously given me 25MPG or higher? Good luck with that.
smirk.gif
 
I also have an '15 Powerstroke and have run nothing but 10w-30 from day one and currently has about 60,000 mi. I tow heavy and haul heavy, every UOA has came back stellar.

As far as MPG differences I have nothing to compare to, but there was an increase in MPG with my 6.0 with 10w-30 vs. 15w-40. I agree with above comments, you'll probably not be able to tell the difference, but you will save money buying 10w-30 and running until the IOLM instructs you to change oil now.
 
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