Ford's 5w30 to 5w20

[Tannerm]

Ok it's oil change time for my 99 5.0 expo and 97 4.6 f150. I have been using 5w30 in both. Doing some digging, ford came out and said that both my vehicles should switch to 5w20. Actually, if you look for what weight of oil to put in either, it will now tell u 5w20... I have the manual for both and both say 5w30 back then.

Question, what negative/positive affects would I suffer from if I switched to 5w20? The 5.0 has 155k and the 4.6 has 176k. Both run perfectly.

(Mobil 1 5w30 in expo, motorcraft synblend 5w30 in 4.6. Both use motorcraft/Bosch/puralator filters)

[91CoupeMike]

Stay 5w 30 for Texas summers

[dumpycapri85]

I agree with Mike Tan not only cause of the heat but also on the mileage . I always ran Mobil one in that expo just FYI .

[jlyon]

i had a 2000 v6 mustang that took 5w30. one oil change, i decided to use ford 5w20 full syn and it gave me a valve train knock like crazy. i drained it out less then 500 miles later and put 5w30 back in and it was quiet again.

[The King]

I would also stick with the weight you' ve been using. I' ve used 5w20 in my Mustang since day 1, but that's what it called for in 2003.

[A_A_G]

My grandparents have a 97 4.6 f-150 that's being using 10w-40 for it's entire life 165k miles. You should be ok, but I wouldn't want to go that thin on a modular engine.

[91CoupeMike]

My grandparents have a 97 4.6 f-150 that's being using 10w-40 for it's entire life 165k miles. You should be ok, but I wouldn't want to go that thin on a modular engine.

That is ass backwards.

[shumpertdavid]

My grandparents have a 97 4.6 f-150 that's being using 10w-40 for it's entire life 165k miles. You should be ok, but I wouldn't want to go that thin on a modular engine.

It's not always a good idea to stray from what the manufacturer recommends. My boss has a hard time struggling with this from his old school mentality. The auto manufacturers do what they can to improve there fuel mileage statistics and a lighter weight oil will help in that (my boss's thoughts as to only why they recommend the light weight oil). There is also the other aspect of that equation, bearing clearances and tolerances. The tighter the motor is build the lighter weight oil needed. If you take an engine with tolerances that benefit from a 5w\20 and dump 20w\50 or some straight 30 in, you could possible starve the bearings.

At least this is the way it's explained to me from the machine shop side of things.

[Tannerm]

Thanks all. I stayed with 5w30 in both. Also learned a hard lesson. When replacing it oil filters, MAKE sure the old gasket goes with it. I've changed oil in countless vehicles and times an never gave this any mind. Well, my explorer dumped all quarts into my driveway due to a double up of gaskets... All good now!

[91CoupeMike]

Thanks all. I stayed with 5w30 in both. Also learned a hard lesson. When replacing it oil filters, MAKE sure the old gasket goes with it. I've changed oil in countless vehicles and times an never gave this any mind. Well, my explorer dumped all quarts into my driveway due to a double up of gaskets... All good now!

I have never had this problem, except for the last 2 motor craft filters gaskets have come off during removal.

[Tannerm]

I have never had this problem, except for the last 2 motor craft filters gaskets have come off during removal.

Yep, me neither. I shit a brick when I started it up and noticed a growing belt squeak and oil smell... I got out and saw buckets of oil running down my driveway. I called Jim and he mentioned the gasket. I checked my old filter and boom, no gasket... Fuck. So, another $30 later and shes up and running. But before I left for vatozone again, I thought It best to check my F150 for the same thing. I was just dumbfounded when I saw the gasket doubled on it too. just wow! Btw, both trucks had different filters on em before and after change. Fluke i tell ya.

[91CoupeMike]

I think they stopped using adhesive on the gasket. It comes off very easy.

Just be sure to always check I guess.

[crapstang]

I always run full synthetic 5w20 in the mach. Anything wrong with that?

[Lone Star Performance]

Crapstang, there is nothing wrong with running the 5w-20. Ford switched to 20 weight for fuel economy. I always run 5w-30 synthetic in ALL of my cars, I would rather have an extra protection over extra fuel mileage, however minuscule either of them may be.

[A_A_G]

That is ass backwards.

Don't really care if its ass backwards, it's worked for many modular motors in my family with 100k+ miles on them without issue, some are getting close to 200k miles.

It's not always a good idea to stray from what the manufacturer recommends.

That's exactly what it is a recommendation, not a requirement. Just like if I had a new 5.0 GT without the track pack I'd be perfectly comforable running a thicker oil. A regular GT specs 5w-20 but one with a track package and the same engine can use 5w-50...