5W-20 vs 5W-30. Is there a difference?

[RPMster]

... or even better:

do the above test with 5 different vehicles, say...

30 Honda Accord I4's, 30 Ford Fusion I4's, 30 Hyundai Genesis V8's, 30 Chevy Silverado 5.3L's, and 30 Mazda6 V6's....

...and see if the results are consistent among all the different vehicles tested.

So... 150 vehicles tested over 150K or 200K miles.

Any volunteers??? C'mon, there's gotta be some old retired rich guy out there with way too much money and way too much time on his hands.

 

[mechtech2]

What say you?

A leakdown test gives better/more valuable results than a normal compression test.
If the slightly thicker oil is giving you 1.5 better idle vacuum, it indicates it is going by the rings, with a lot of blowby. It could also be air admitted past the valve guides, and the thicker oil also helped.
But those parts are new, and should not be leaking that bad.

My bottom line is that although you did indeed see an increase, it probably was not a good repeatable test concerning the very similar oils. All sorts of things could account for the difference.

 

[wiswind]

Lambrose,
From all I have read....that 3.0L Vulcan motor is a very solid, reliable motor and there a MANY of them out there in a variety of applications.
If you are seeing a problem with the 5W-20, I would have to agree that something is amiss with the motor.
FORD did not include several motors/applications from the switch from 5w30 to 5W20.
I do not remember which ones.....but none of them were the 3.0L from what I remember.

As for the advice about Auto-RX, I have used this in my 3.8L Windstar, and it does clean things up.
I did not have any performance issues before hand.....so I cannot comment on performance improvement.
I DID switch from using 5w30 (Mobil 1) to the 5W-20 (Mobil 1) as recommended by FORD.
I now use Redline 5W-20 (overkill).
I have 217K miles on my van/motor, and I think I must have been around 110K-130K when I made the switch.....with no issues.

If it were me.....I would give the Auto-RX a try.....follow the instructions on their website.
If, as has been suggested, you have issues with the rings that could be cleaned up with Auto-RX.....it is a VERY cheap repair.....and I have to believe that it is an issue with either weight of oil.....even though you seem to see it more with the 5W-20......for the cost.....it is worth a shot.

 

[lambrose]

I may look into the AutoRX. I do not think there is any piston or ring damage. Also the truck uses up NO oil between OCI's. no smoke and does drive great. I just wonder why Ford switched oil recommendations. I refuse to believe it was for better protection, but for economy only. there was no reason for the switch other than that. I doubt that Ford got the wrong grade oil in 3/4 of the fleet and it took years to figure this out. Something had to drive this change, ie. GOV CAFE regulations.