Use 5-30 and call it a day.

When I bought my 97 5w30 was what Ford recomended and on the sticker under the hood and that's all that's ever been in it and at 155K miles now and uses maybe 1/2qt. @ 3k intervals but it has done that since day one. My 06 is using the semi synth motorcraft 5w20 and has 115K and doesn't use any at 5k intervals. We have an 03 E250 that uses 5w20 and has 295k on it and our operations manager just sold his 05 F150 and it has 349k on it. I agree with Jimmy and Titanium I use what the factory recommends on a factory engine. Now if your rebuilder built up a super hot rodded high lift cam twin turbo rocket launching engine then maybe I would follow his recommendation then.

Like 1 master tech said, this master tech says the same thing. if the cap says 5w-20, use it. thats what they are designed to have. anything else can/will cause problems. hth

As a shop owner and Master tech myself, I've never heard such a thing. I think I would get some kinda explanation as to why they want you to use that kind of oil! Most cars and trucks now days use a 5-20 or 5-30. According to Ford, it is supposed to use 5-20. If yours has the cam phasers, then it is most likely to set codes and cause issues. Just my 2 cents!

Okay, I'll stick with the synth blend of 5W-20.

After reading the warranty agreement word by word (for the 3rd time), there's not mention that I need to use heavier oil.

Jimmy & Titanium, many thanks for your input.

+1, I had to switch to 5-30w on my 2001 5.4. Oil consumption went down by half vs. the 5-20 syn blend. Not sure what it is about the 5.4s. While I hear people bragging about them I also know there are some real crummy ones out there. Mine just happened to be one of the latter.

In this case, the Multigrade viscosity can be defined as 5W when Cold and 20W when hot. You want thinner oil when cold, and thicker oil when hot. 20W is a relatively thin oil anyway. When the manufacturer recommends an oil, who knows what conditions the vehicle will be used in? That said, I would still subscribe to the theory that when I'm running long periods of time and the engine is warm, I want a thicker oil. I just don't see 20W as a thick oil. 40 W is thick.

I run a fleet of Ford pickups, from a 95' F 350 7.3 diesel to 08' super duty V-10. We run factory recommended oil (5w 20 semi synthetic) in the gas engines. Lowest mileage truck has 70,000 miles on it, an 08' SD F 250.Highest mileage V 10, 250,000 miles identical truck 99' year model. These are work trucks and pull loaded trailers a lot of the time. We do all of our own service and these trucks have never given us a moments problem. I am a believer in the owners manual.

Your welcome Adan V.... anytime.

I would run what the manufacture says. Chances are good they have done testing and research to figure out which oil weights are the best for their engines. Unless they come out with a TSB saying to run something else I'd stay OE on oil and filter recommendations. Only exception I may make is running Mobil 0w-20 instead of the 5w-20 or maybe doing 5w-30 if I felt I needed thicker oil.

No offence but what you think doesn't matter. You do understand the differences in bearing tolerances and variable cam timing being affected by specific oil pressures at specific rpms right? The engine was designed to run with that weight oil to provide proper lubrication of a close tolerance motor. Sure when rods were clearanced to .040 30 years ago everyone ran 30 weight, now it's more like .015 (varies depending on application but they are all tight) and a thicker oil is actually detrimental to lubrication.

Run what you want but you'll do much more harm than good.

he wants you to run 60 weight in a freshly rebuilt motor? either the guy doesn't know what he's talking about, and you should fear for your engines rebuild quality or he put an old junk yard motor in their that smokes and is telling you to use the thick oil so you wont see that the rings are gone. there's no reason to move away from ford recommendation. there is a lot of stuff ford took into account when recommending an oil. the most important being the cam chain tensioner, which increases tension as oil pressure increases with rpms. if your tensioners allow enough slack in your chain it will skip a tooth on one of the cam sprockets, and allow your valves and pistons to have a boxing match.

I would have a hard time believing that anyone that knows anything about automobiles would reccomend to run 60 weight engine oil. $$$$ that aint far from gear oil! Run what the manufacture calls for. 5w 30 would be ok also.

Whoa, you need to slide some of your decimal points to the left a few notches. .040 might have been a good spark plug gap 30 years ago. Rod clearence on a new or rebuilt engine would have been in the .0005 to .003 range. When

ford first started using 5w20 oil the engineers admitted that it sacrificed some engine wear for increased fuel efficiency. Now the synthetic blends might be different. I have an 05 4.6 Ford engine and manual recommends 5w20 but I have never put anything in it but 10w30 and it's a little over 92,000 on the odo. s

slodsm is right. Older engines tended to have looser tolerances than today's engines. The tighter the bearing clearances, the thinner the oil needs to be to reliably penetrate that surface. A side effect is that a thinner oil is easier to pump and has less parasitic drag on internal parts, freeing up a little power.

I run 10/30 in my older stuff even 20/50 in the Ford 8N, I would not even consider putting it in the '04 Nissan or the '07 F150. Almost guaranteed to cause low end damage. 5w/20 it is for both of them. And I would never consider running that stuff through a gen 1 SBC or my 8N tractor.

If oil consumption is the problem, cylinder wear is the likely culprit, and running thicker oil only masks that while starving the more important bearings in the low end.