Just curious as to thoughts on here. Engine has 140k miles and seems to be running well, but seeing conflicting things online as to what viscosity oil to use. Manual says 5w20 but a lot of people recommend higher viscosity to ward off potential phaser issues and for other reasons.

Would I be better off running 5w30 or even thicker option moving forward? And does it matter full synthetic vs synthetic blend?

FORD USER Manual specs >>>>>>>>>>>> internet bubbas opinion.

I really don't think any of it makes a hill of beans worth of difference. My 77 F250 runs 10w30, my newer fords want 5w20. On the ones that have 200k+ miles I run the cheapest synthetics I can find on clearance or sale but that still meet OEM spec. For my ford that has 455,000 miles, I literally dump in whatever I have around. 5w20, 10w30, 10w40, SAE30, 15w40 rotella, 10w20….i don't care. There are times I'll combine 6 jugs of whatever is on my shop shelf just to fill the crankcase. Still chugging along on the original motor.

Modern oils are not like grandpa's.

I have 380k on my 5.4 running 5w20 Mobil1 ever 5000 miles.

GrapevineAg said:

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The manual/manufacturer specifies a lighter weight oil to improve fuel efficiency a little. I think you'd be fine running 5w-30, but just run what it says. The important thing is to change it and the filter regularly.

Edited to add: I always go with full synthetic. Only a few bucks more for peace of mind.

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Don't change to full synthetic if it has been running conventional for 140k. Use high mileage conventional like Penzoil High Mileage.

Yeah, for a modern engine (2014 in this case), it won't be an issue.

Good dialogue here.

I'll probably stick with the 5w20 for now but if I do switch, it'll be to 5w30. Interval seems more important than the oil itself is what everyone's consensus seems to be.

Three of my four vehicles spec Ow-20 and they all are running 5w-30. I think the Chevy debacle with now having you use heavier weight oils than spec'ed should tell you why the thin stuff is all about fuel mileage and efficiency. Sure, the light stuff will get you through the warranty period, but after that the manufacturer could care less about engine wear.

EDIT: Shoot, the 6.2 engine isn't even making it out of warranty period.

Martin Q. Blank said:

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BrazosDog02 said:

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FORD USER Manual specs >>>>>>>>>>>> internet bubbas opinion.

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User manual specs are meant to meet CAFE standards, not protect your engine. I think there was a discussion on here about Toyota specs in the U.S. vs. Australia. 0W-20 here, 15W-40 in Australia. Same engine.

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