Just traded my f-350 for a screw 4x4 f-150 with 5.4. I was looking in the owners manual and it says 5w20 oil only! This sounds kind of thin to me. I was expecting it to say 5w30. Would it hurt to use 5w30? I always use synthetic if it matters(will not say the brand since sometimes it starts a brand discussion).Thanks in advance.

 

i have a 2006 f250 sc LB 5.4l 3v and for my first oil change i used 5w30 just becasue the dealership gave me a case of 5w30 when i asked for 5w20...anyways i didnt notice it untill i alady changed the oil...i changed it this past time...only my 2nd...i used 5w20...i was all concerned and i was searching around the internet and i found that ford uses 5w20 to meet the 128 min. ASTM sequence III test and that it really doesnt matter if you use 20 30 or 40...i hope it helps

 

It also gets to the heads faster on start-up to keep valvetrain wear to a minimum. I've used it in my 01 5.4L since I got it (5W20) and tow alot of weight in hot weather and the a/c on and have had no problems in 64,000 miles.

 

What is the ASTM sequence III test? Since when the oil is cold it flows like a 5w(winter weight) I believe I may go ahead and use the 5w30. I have read that the manufactures use these lighter weights also to raise fuel economy. Thanks for the help.

 

OK, but using the thicker oil may also void the warranty if something oil related were to happen. These newer engines also have tighter tolerances so thicker oil is not needed.

 

I think if Ford recommends 5/20 weight oil they have a reason for it.I have also been using it for a long time with no problems.

 

Just use whats recommended...

 

Here is some good reading on the 5W20 oil
https://www.ford-trucks.com/forums/s...4&page=1&pp=15

 

Alot of guys have gone over 200k with 5-20w motorcraft oil in the 5.4 , some 300k+ .