joeinmn

I've heard rumors of a TSB calling for the change from 5w-20 to 5w-30 but have never seen it. Nobody has mentioned it so it must not be true. I've been running Napa full synthetic 5w-20 for a few years now along with the Napa gold filters which have the check valve i believe. I change oil every 8000 or so, but have to add a couple quarts between changes because it uses some. 284,000 miles on the original motor. No new vvt parts yet. 2005 5.4.

coolride

anybody think it would be good for the engine to use thicker oil if you use the phaser lockouts? Seems the phasers are really what needs the 5w20? without utilizing the VVT system it might be good to use thicker oil on a high mile engine? I currently use 5w20, but might be going to livernois locks

Jayman1989

i honestly like 5w-20 royal purple oil. i resently switched to 5w-30 in my truck because the local ford dealer said that it would stop the light tapping noice i have been hearing in the timmies drive thru. but no real change. i have notice its a bit harder on fuel. went from 16L/100km to 19L/100kms so im switching back. when it come to protecting your engine 5w-20 does really well. even tho they say 5w20 is a 5000-8000mile oil i still change at 3000mile (5000km) i also got a 2004 freestar with 530000km runs of 5w-20 royle purple not one engine problem. still runs smooth and quite!! so 5w-20 is my vote

Martian

The TSB stated to switch to 10W-40, and that TSB is no longer valid.

Martian

I switched back to 5W-20 over the weekend. I saw no performance differences with 5W-30.

coolride

I think it seems as if Ford recommends the 5w20 to help the VCT and phasers react fast enough to keep the PCM happy. I just locked my phasers out, and I am running 10w30 Motorcraft blend. I won't be going back to the 5w20. I am in SC, it will be getting really hot here this summer. Not running already thin oil in a 200K mile engine. If it were new, maybe? But its not. I'm just old school, thicker oil in worn engine =good! lol

bbrad1775

Did you see a loss of MPG with the thicker oil?

Martian

It'll still be lubricated with either one, the only real difference will be a slightly slower flow rate and the higher viscosity will seal any leaks a little better. Running the 20 won't make the engine hurt itself or anything like that, it'll just make things like possible ring issues come to light.

TOPGLOCK

Has anyone developed any oil leaks after switching to full synthetic on a high mileage 5.4?
I thought this was a myth until I've read several complaints about this very topic. But I haven't seen anything on the 5.4.

I would like to switch to mobile1 for the summer since I pull so much with the truck.

ak_cowboy

Try using the Mobil 1 High Mileage synthetic.