whats the point of using a 50w in the engine? its not going to give you added protection over 5w20. take a look over at bitog and look at some of the mod engine test results all of them show higher wear numbers when you go over 10w30 and they all show very nice looking numbers when you use 5w20.

 

Motorcraft 5w-30 oil and filter

 

1999 5.4 Expedition. 5w30 since we bought it at 50,000 miles about 2 1/2 years age. About 80,000 on it now. Motorcraft 820S filters. Uses about 1/2 quart in 2000 miles.

 

15W as a base stock is a bit thick for start-ups on a modular engine. You want oil to the top of the engine as soon as possible due to the overhead camshafts and such.
Oil is designed by using a base stock number say 5W for instance and then has additives to make it a certain thickness when hot = 20.
So 5w20 flows like 5wt when cold and 20wt when hot.
15W40 is thicker when cold 15wt and will not reach the top of the engine as fast when cold and 40wt when hot is not required.
I have towed 7000lbs in 98degree weather with the a/c on and have never used any oil between changes and have had no adverse effects from the 5w20 in 54,000 miles.

 

Motorcraft 5-20 since new. 51K today, no problems. (knock on wood)

gw

 

havoline 5w-30 with fram tough guard filter...181k

 

Motorcraft 5-20w/fl820s filter -10k miles.

 

5w-20 motorcraft

 

Origional owner ran 10w40 (or was it 10w30?) since he bought it new. I havent had it long enough to do an oil change.

 

A good Ford mechanic that I know recommended using the Motorcraft 5W20 synthetic all year for the 4.6

 

Ford390gashog,

Do you have a link pointing to the wear tests between the different oils? You mentioned it in your other post.

 

Mobil 1 5w-30 and FL-820S filters since new. No problems or oil consumption.

 

Motorcraft 5W20 with FL-820s filters only 18,000 miles to date.

 

Just switched to Mobil1 5W30, and the MC 5W20 looked nasty when I changed it.

 

i live in south texas and i have always used 20/50 in all my trucks doesnt get to cold here. in colorado for 7 winters sure we used the lower viscosity. havent heard that this is bad .