Using 5W40 instead of 5W20

[Y_K]

Amateurs argue the case few professionals can agree on, with a speck of a dogma thrown in here and there.
On a side note: Ford is not only a 'manufacturer', it needs to sell the product, and, along the way, avoid Gov penalties.
As for 7% variance in mpg, check your spark plugs, tire pressure and get a good graphing code reader.
Good point on lower rpm and higher torque..
After Ford moved to lower viscosity, it had to increase sump capacity by 20% in Panthers. Use your head instead of repeating hearsay with authority.

 

[Falcon_LS]

I have used a range of different viscosities in my Modular 4.6, from 10W-30 to 0W-40 and 5W-30 to 0W-30 respectively with little to no difference in fuel economy. I do not follow API and ILSAC standards, but rather focus on ACEA A3/B3/B4 or A5/B5 based lubricants instead.

Whilst Ford recommends 5W-20 for these engines in the States, 10W-30 is what they recommended for these engines in the Middle East. Motorcraft 5W-50 is in fact specified for some applications. In Australia, 5W-40 is recommended as a premium oil for these engines.

At my next oil change, I'm looking at Liqui-Moly Synthoil High Tech 5W-40. Personally, I'm not just looking at viscosity, but base oils and additive packs as well.

I'm not arguing thicker or thinner is better, but provided you use a sensible viscosity (e.g. not a 15W-40 in Canadian winters and not a 20W-50 in a modern engine that isn't used for racing applications), there shouldn't be a problem.

 

[crinkles]

Originally Posted By: Steve S
Originally Posted By: uart
Originally Posted By: Gokhan
It won't harm your engine. In Europe they recommend anything between 0W-20 and 20W-50 for engines that strictly call for 0W-20 in US.


Same thing here in Australia. These are scanned images from my (original) owners manuals for
1. 2005 Mazda 2
2. 2005 Prius.



Uploaded with ImageShack.us
That is because everything is upside down in Aus!!!

Seriously considering running M1 5w-50 (yes, fifty) my next OCI for 10,000 miles

 

[OVERKILL]

Originally Posted By: Y_K
Amateurs argue the case few professionals can agree on, with a speck of a dogma thrown in here and there.
On a side note: Ford is not only a 'manufacturer', it needs to sell the product, and, along the way, avoid Gov penalties.
As for 7% variance in mpg, check your spark plugs, tire pressure and get a good graphing code reader.
Good point on lower rpm and higher torque..
After Ford moved to lower viscosity, it had to increase sump capacity by 20% in Panthers. Use your head instead of repeating hearsay with authority.


Don't forget the factory oil coolers!

My Expedition spec's 5w20. It also has a large oil cooler and 6L sump.

 

[uart]

Originally Posted By: ericthepig
Originally Posted By: crinkles
I've had my best mileages in 5 years using 15w-40.


Makes no sense, but me too. 15w40 (Schaeffers) in the Sienna - best mpg ever - close to 26mpg HW (very few data pts though). I now typically run slightly above 5w20 visc (mix of 5w30 and 5w20), and I see 23+mpg max.


That's interesting, I see that both yourself and crinkles are from somewhere with a warm climate.

I know a lot of different figures always get thrown around here when this subject of fuel economy versus oil grade comes up. One thing I've noticed is that people in warm climates seldom notice much (if any) negative impact of running a thicker oil. I'm not just talking about the two users quoted above, but also anecdotal evidence from various people in different climatic conditions. I seem to be seeing a consistent story, a small but sometimes noticeable reduction in FE for those in a very cold climates but very rarely any noticeable effect for those in a warm climate.

So I'm pretty sure that the issue is mostly where the car is run for a significant amount of time with the oil well below normal operating temperature. We've all seen the viscosity versus temperature curves and know that it's down at the low temperatures where the huge increases in viscosity occur, and where there's also huge viscosity differences between grades.

Where I am in Australia we operate in summer temperatures up to about 45C (over 110F) and xW40 oils are the norm and seem to work well.

 

[sleddriver]

Originally Posted By: MMasz
I‘m considering using Rotella T6 5W40 in my Expedition on my next change instead of 5W20. Will this affect my gas mileage?

Thanks in advance.


Hard to say. V8? or V6? Towing? Hauling? On the other hand you are in Florida, where it gets really hot & humid. The asphalt alone can heat up to 130+ F. Sitting in traffic, with the AC on high, someone else's hot exhaust going through your radiator/condenser/transmission cooler stack.

I recently picked up a jug of T6 5w40 on sale at WM to use in my Volvo turbo wagon. It's in there now matter of fact. Just in time for typical Tx Summer: 104F in the shade, 120+ F in the sun, and that incredibly hot asphalt underneath it all. But my 2.3L, 5-cylinder mouse-motor has to work a bit harder than a large V6 or V8. And eventually, all the oil makes a trip through the turbocharger housing, which is very hot. Fortunately, there's also an engine oil cooler.

Being in Florida, in the Summer, in this heat? Don't think you have any worries.

 

[MNgopher]

Originally Posted By: Y_K

As for 7% variance in mpg, check your spark plugs, tire pressure and get a good graphing code reader.


After returning back to 5w30 oils in that truck, fuel mileage returned to its previous level and stayed there for the remainder of the years I owned the truck (just sold it in December with 194,000 miles on it). Also note the experiments were run over a 1 year periods with normal maintenance. Vehicle was maintained well - after all, we're on BITOG.

As I noted before, it gets cold here in the winter (does not apply to the OP) and I was doing the same experiments in my Jeep Cherokee at the time, which noted no decrease in fuel mileage between 5w30 and 5w40 oils. My theory had to do with the fact the Jeep 4.0 in Cherokee is marginally cooled under the hood to begin with and there was plenty of over capacity in the cooling system in the F150 with the 4.6. Yes, the thermostat theoretically holds an engine at temp, but with -20F air (Actul, not windchill) rushing over a cooling system it may not actually stay at temp well, where the Jeep certainly does.

It is what it was in that truck. Your mileage may vary, but I am pointing out a case where there was significant impacts (fuel mileage wise - none mechanically).