I have a 2000 Ford F-150 5.4L 4X4 supercab. The manual recommends 5W20 engine oil. I have been using 5W30. Does it really make a difference?

 

better gas milage , youll be fine . i run 5 w 30 in my sd witch calls for 5 w20

 

+1, 5w30 will be fine and the gas mileage difference is very small.

 

I work at a dealership. And we don't even use 5w30 any more. Even in vehicles that specify 5w30, we just put 20 in it. you will never notice any difference.

 

Interesting, maybe your Dealer is just trying to cut bulk storage lube costs, or maybe they haven't read the engine exclusion table at the bottom of TSB 02-1-9, in which some Ford engines aren't to use 5W-20, or the Q&A letter from Ford to the Dealers in which the reasoning behind the exclusion of some engines not being ok to use 5W-20.
https://www.ford-trucks.com/tsb/full...php?tsb=02-1-0

The reasoning in the Q&A letter behind some engines being excluded, is that their oil pumps havent been upgraded to be abe to provide enough flow/volume, of hot 20wt oil, to a warmed up engine & that some engines will never be able to use 5W-20!!!!

You'll have to scroll down toward the bottom of the letter to find the oil pump Q&A.
Lots of other useful info in the letter too, so it's worth the time to read through all of it imo. You'll probably have to blow it up to read it.
http://www.dantheoilman.com/fordoilfaq.doc

This Motorcraft oil has been wrung out pretty danged good by Ford engineers & folks from all over the country using it in all kinds of engines & under all kinds of conditions, are turning in some mighty good UOA & mpg numbers, so if our engine is specified to use it, I don't see any reason not too.

I'm still using the ogionally specified 5W-30 in my 3.8L Taurus, even though it's ok to use the 5W-20 under the TSB, because my Rangers 4.0L isn't to use the 5W-30 because it's oil pump hasn't been upgraded to use the 5W-20, so it's easier for me to just use one viscosity range lube for my rides.

More thoughts for pondering.

 

No use whatever is on sale

 

I don't use whatever is on sale! I care about my truck!!

 

Actually, it's hard to find a "bad" 5-20/30 oil; they're the hot sellers currently, and the mfr's are trying to outdo each other.

I'd run MC 5-20 with a MC filter (assume yours takes an FL820S) and sleep well at night. Actually, we do just that with a variety of fleet vehicles, and have for quite a while, with no issues.

 

I run what is recommended for the vehicle when manufactured. I've got 5w-20, 5w-30 and 10w-30 on hand for different vehicles I have. Would it be easier to run one weight in all? You bet but I don't and never will.

 

I should have said "a quality, major brand SM" oil on sale

 

Another thought, if we check the hot 100c viscosity specification figure of our 5W-30, we could choose a brand that uses a better quality base stock, that can have a safe hot viscosity figure thats on the low end of the 30wt scale (like 5w-30 Havoline @ 9.7cst, or others), or another way to think of it is, that it's on the upper end of the hot 20wt viscosity scale, so we can reap the hot film protection of a 30wt, with the easier flow of a 20wt, such that maybe we could split hairs & realise lower pumping losses & maybe a small gain in mpg.

Some 5W-30 lubes have hot vscosity numbers way up on the 30wt scale, such that they are more like a 40wt at hot temps.

Some viscosity tweaking thoughts for pondering.

 

i just buy a couple of jugs of MC 5W-20 every few months and run it in my 2001 Civic EX and 2001 F150 5.4L