Question about Ford Engines and 5W-20

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After reading the thread about the police cars, a question popped into my mind: What is it about Ford engines like the 4.6L V8 that can use 5W-20? I understand the whole thing about tight bearing clearances requiring a thin oil, but don't all new engines have tight bearing clearances? What would happen if a new GM or Toyota engine was ran with 5W-20 oil?
 

GoldenRod

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Ok so if Ford and Honda use it, then why not every other auto manufacturer on the planet? Why hasn't 5W-20 made all the other oil weights obsolete for (new) engines?
 

JTK

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Ford, Honda and Daimler-Chrysler are on it. Wont be long before GM reprints the owners manuals and re-stamps the oil filler caps to spec it too! Joel
 
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quote:
Originally posted by GoldenRod: What would happen if a new GM or Toyota engine was ran with 5W-20 oil?
Nothing. The 3.5 in my Chrysler is spec'd for 10w30. The manual says 5w30 can be used at temps below zero. I've been using 5w20 in it for over a year with great results. You can do a search and find my UOAs posted in the UOA section. Just for the heck of it, when I did the Auto-RX treatment on my Olds mini-van I used Pennzoil 5w20. Even with well over 100,000 miles on that 3.4 it ran just fine on 5w20.
 

GoldenRod

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Ok then what about older engines originally speced for 10W-30? Would it be safe for these engines to use 5W-20 as well?
 
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quote:
Originally posted by GoldenRod: Ok then what about older engines originally speced for 10W-30? Would it be safe for these engines to use 5W-20 as well?
If we're talking about mid-70s pushrod Detroit iron, I don't think I'd use 5w20 in it. But I think virtually any modern engine produced from around 1990 on could safely use 5w20 under most conditions.
 
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quote:

Ok then what about older engines originally speced for 10W-30? Would it be safe for these engines to use 5W-20 as well?
quote:
Ok how about a year 2000 pushrod engine that is speced for 10W-30? Or do you think that 5W-20 is just for OHC engines?
No matter how you word the question, the 5W-20 is ok, dood. My 2005 specs 5W-20, but 5W30 is spec for the over 35 degree season as well. ALL the cars (ok, ok, so there's an exception to the rule somewhere) spec 5W-20 now, if only as a nod to the CAFE requirements.. Bottom line is, do what the book tells you. With 5W-20, will you get better mileage over 5W-30, or 10W-40? Maybe, but who's going to prove it? Where's the control? How to compare? And what's the difference, 1 MPG out of 25?
 
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I believe that better metallurgy and use of roller-cams in engines is the most important ting. I would not use xxW-20 oil in older designs.
 

GoldenRod

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So with that being said, there must be something else to a motor oil other than good gas millage, otherwise, everyone would be running their engines with 5W-20. I here about a lot of BMW owners running their engines with thick oil. Why? What would happen if they were to run their engines with 5W-20?
 
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GoldenRod, European manufacturers just spec high viscosity oils. They've been doing that for as long as I've been alive. With as many engines as BMW makes and sells, I'm sure some of them would do just dandy on 5W20, while some might really do better on synthetic 5W30 or conventional 10W30. And of course, one engine that has been retroactively specced for 10W60 will continue to do poorly no matter what you put in... :-) One thing to think about is that if you're expecting really high oil temps, you can spec higher viscosities just as safely as lower ones. If you expect your drivers to be running 110 MPH for an entire trip (certain European highways) or competing in races lasting more than five laps, then running viscosities the next notch up may make sense.
 
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Tom, I think you hit one aspect, higher operating temperature. One other point, while I doubt many people would have a problem running 20 weights, there may be some differences in oil pump design that favor heavier oil. I don't know this, just a precaution. I CERTAINLY do not doubt engines spec'd for 20 weights are perfectly fine to run them in.
 

MolaKule

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If one is seeking slightly better mileage, I would recommend you run a 5W20 with UOA's to determine if the engine likes it. Also listen to the engine and see if the 5W20 quietens the engine or makes it tick louder, less noise, etc. I think you will be suprized with some of the new 5W20's.
 

GoldenRod

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Ray H, Rest assured that I will never pour 5W-20 into my motor. I was just trying to get to the bottom of the issue of what technical aspirations that allow Ford and Honda to use 5W-20 in their engines. So far we have nailed it down to bearing clearances and internal oil pump clearances. What else?
 
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On the topic of Fords and Ford engines, A co-worker today arrived at our home office in his 2004 Ford Focus. He drives it daily, on the job. It is 18 months old. Current mileage is just short of 65,000 miles. I didn't fully interrogate him, but he said he changes the oil every 5,000 miles. I didn't quiz him on what kind or if he does it himself. His miles aren't wholly highway miles. I would say over 20% of the time the car is running it's idling. 40% of the mileage is probably stop and go. The remainder is highway. It is used for work pretty much exlcusively. We went to lunch in the thing and it was very quiet. No noise whatsoever. I was impressed. I was also shocked. 18 months old and 65,000 miles.
 
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quote:
Originally posted by GoldenRod: Ray H, So far we have nailed it down to bearing clearances and internal oil pump clearances. What else?
Well, I didn't mean oil pump clearances, I meant pump design and rates of flow/pressure. Hey, how about this? The newer SM 5W-20's are BETTER! [Eek!] OR, how about this: we are finally returning to our roots when straight 20 weights were used! When the multigrades began to be used, for example, the 10-30's, they sheared fairly soon to a 20 weight anyway! I'm of the mind it would probably be OK to run the new SM rated 5w-20 in my two Subaru engines. BUT, I won't, due to warranty reasons. However, in a couple of years, when more and more information comes out about these new SM 5W-20's, I would not be surprised one bit that many cars are back-spec'd to the these oils, like Ford has done.
 
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