New Fords state 5w20 for their engine
I wonder if it is for best for engine or best for CAFE requirements...?
I have done hours and hours of research....reading...looking at oil lab reports...
This is my last new vehicle purchase most likely and I'm looking for engine longevity.
A 5w30 breaks down pretty quickly into a 5w20 and in my opinion viscosity protects engines.
I have heard all the opinions that ford engineers know what is best...but is it best for cafe requirements ....or best for engine protection and longevity?

I believe 5w20 will do for 100,000 miles but for the long haul I think the thicker 5w30 might be the answer for long term engine protection.
Oil passages...bearing clearances...they really aren't at issue as European spec the 5w30 or higher in the same engines.

Opinions.

 

In my 2019 F-150 owners manual Ford states 5W30 not 5W20.

Specifications
Materials

Name Specification

Recommended motor oil (U.S.): WSS-M2C946-B1
Motorcraft® SAE 5W-30 Synthetic Blend Motor Oil
XO-5W30-QSP

Recommended Motor oil (Canada): WSS-M2C946-B1
Motorcraft® SAE 5W-30 Super Premium Motor Oil
CXO-5W30-LSP12

Recommended motor oil (Mexico): WSS-M2C946-B1
Motorcraft® SAE 5W-30 Synthetic Motor Oil
MXO-5W30-B

 

My oil fill cap 3.3 engine says 5w20
Beginning to wonder ?

 

Use what the manual states or risk voiding your warranty. Nothing else needs to be said.
.

 

Yes for 36, 000 miles but after that....what is best ?

And frankly an engine oil analysis on a 5w20...vs 5w30 after use would be so dubious...I doubt any warranty could be denied due to the oil. In fact I never heard or read of one ever...on the internet or elseware.
Just internet ....responce type of repeat information.

I'm talking long...long term use

 

Pretty sure the EcoBoosts call for 5w30 and the naturally aspirated 3.3/5.0 for 5w20

 

Turbos are hard on.engine oils by their very nature

 

I run 5w30 in 5.0. If you look in the owner manual you might find a chart that show various viscosities for different temperature ranges.

 

In the past 20+ years of my career I have found using the wrong weight oil can cause issues such as knocking, tapping. We had a couple hard core old school gomers come in and demand the weight oil they wanted for the change so we obliged them.

Every one of them came back less than a week later complaining of engine noise and that we messed up their engines. So we walked them back to the service bay and let them watch us drain and refill their engines with the proper weight oil and all but one of them came back to thank us for showing them that the engineers that designed the engine knew what they were doing.

Not sure on the last one, he probably had his *** on his shoulders that he was dead wrong.(he demanded 20/50 because it was summer) The manual called for 5w20.

Your engine, you make the call but from my professional opinion if you use the wrong weight oil regardless of miles, you're asking for trouble. I've only built a handful of engines over the span of my 40 year career, 11 as a Ford line tech.

The tight tolerances of today's engines are just that, you try to push too thick oil thru them and they starve.

You can spin your response any way you like but my answer remains the same. Use what your manual states.
.

 

My Jeep 2011 jerp Wrangler called for 5w20 I thought that was insane .....been running 5w40 in it going on 75000 miles zero proplems.
This was in Florida with high temps
Back now in Ohio I'm running 5w30 in it...seems to be doing well