Why does Ford Require 5W30 in the 4.0L SOHC?

[stranger706]

I'm not digging up links but I've read several times on Ford forums that this particular engine/oil pump combo was not suited for 20 weight oil and they did not want to re engineer a new oil pump.

Don't forget this engine had already been enlarged from the 80s, then SOHC added during the 90s so the oil system was likely just about maxed out.

This engine has 3 timing chains BTW. 1 short and 2 long. One of the long ones is in the back. It was part of the conversion to SOHC. The short chain turns the jackshaft. The jackshaft turns the 2 long chains.

Edit: Forget to add, oddly enough the 4x4 versions of this engine have a 4th chain going to a balance shaft.

 

[CATERHAM]

Originally Posted By: [/quote

There are some engines however that even with great oil pressure 0w20 and 5w20 can't protect even at sub 100c oil temps.

I hear this type of odd contradictory statement from time to time from drivers that don't know how to properly read and interpret an OP gauge assuming the gauge is fully operational, some aren't. And/or they simply don't understand the concept of operational viscosity.

Oil pressure tells you what your operational viscosity is ever second an engine is running at all rpm levels, not the oil grade. An engine doesn't know what grade of oil is in the sump just what the actual viscosity is and that is predominately determined by the oil's temperature. With that info' one can make a more precise determination if you are in fact
running a light oil or heavy oil.

 

[turtlevette]

Just something to ponder.

Transfer cases with the chain drive are using ATF now. Much higher loading than turning a camshaft. ATF is really thin stuff.

 

[demarpaint]

Originally Posted By: turtlevette
Originally Posted By: demarpaint
Originally Posted By: Shannow
I'm interested in how oil pressure and temperature can be used to determine how the cam chains are faring with this overly thick oil...given that seems to be the reason for Ford's engineers getting it wrong in not specifying a 20.


Good point. The way I see it is can't give you any clue as to how the chains are faring unfortunately. Those two gauges tell part of a story, not the whole story. It's like going to the doctor for an exam and he checks your blood pressure, and temperature, and nothing else. He sees it's OK and sends you home with a clean bill of health.

If oil pressure and temperature can determine how the chains are holding up I stand corrected and would really like to learn how.


I don't think that's what he is saying.

And if the thick oil recommendation by Ford is to prevent chain noise, I'm really not interested in selecting an oil based on sound.




I doubt Ford selected the thicker oil for sound reduction, although it might have been a small factor. It could very well be because of issues with the chain, or simply that a 30 grade oil is the better choice for that particular application. It could be because of the chain, oil pump, bearings, rings, etc. or any combination of those parts and others. The bottom line is I would stick with a 30 grade oil in that application.

For the record, that doesn't make a 20 grade oil bad, it's just something Ford decided against in that engine.

 

[SteveSRT8]

Originally Posted By: turtlevette
Just something to ponder.

Transfer cases with the chain drive are using ATF now. Much higher loading than turning a camshaft. ATF is really thin stuff.


Think "size" and "speed" and you'll see a transfer case chain is so big and moves so slowly there is little to compare...

 

[Shannow]

Can also think "additive types", and "activation", and the constancy of torque transfer (versus a valve train doing the "hoochie coochie" to quote Smokey), and engine ingesting and creating particulates...there's nothing remotely similar

 

[Brent_G]

Originally Posted By: CATERHAM

I hear this type of odd contradictory statement from time to time from drivers that don't know how to properly read and interpret an OP gauge assuming the gauge is fully operational, some aren't. And/or they simply don't understand the concept of operational viscosity.

Oil pressure tells you what your operational viscosity is ever second an engine is running at all rpm levels, not the oil grade. An engine doesn't know what grade of oil is in the sump just what the actual viscosity is and that is predominately determined by the oil's temperature. With that info' one can make a more precise determination if you are in fact
running a light oil or heavy oil.



I understand however the OP gauge only shows part of the equation - does it show the temporary shear and viscosity loss in areas like the upper rings? KV40 and KV100 are important yes however do not take into effect HTHS.

Oil pressure is influenced by the oil viscosity (Not HTHS), filter, temperature, and wear in the engine itself. The gauge will not show the minimum oil film thickness or the actually viscosity of the oil under mechanical pressure and cyclic loads in areas such as rings, bearings, cam, etc.

 

[threeputtpar]

I guess I was a bit too passive in my response to the OP's original question. And even though he's long gone now, I'll clarify my statement.

When our timing chain pads and tensioners in our 1999 4.0 SOHC pooped the bed, we had the truck towed to the FoMoCo dealer that my wife originally bought it from. They knew immediately by ear what was wrong with it and how to fix it, so they gave us a pretty good trade amount on it.

The oil pump is barely good enough to keep everything lubricated properly, and even with 5W-30, the chains, plastic tensioner pads and the tensioner itself have a less than optimal chance of lasting the 300k miles that everyone on this site quotes that timing chains should last. They told us that this issue had a probability greater than 50% of occurring, and that increases if one was to go longer than 5k miles in the oil change regiment.

This info was straight from the service techs at the dealer, who have so much practice repairing this design fault that they can do it in less than 50% of book time. That's why they were willing to give us normal trade value for the vehicle.

Of course, Ford never admitted the design faults so there are no recalls or TSBs on the issue. All the public has to go on is what the service techs have found through trial and error and repeated diagnosis of the all too often occurring problem.

 

[Maritime Storm]

You also must remember timing sets were redesigned on this engine in late '02 to help them last longer. I guess I'll stick with 5W30 on it. I figured their had to be a reason, but I had no idea what it was.

 

[SteveSRT8]

Originally Posted By: Brent_G
Oil pressure is influenced by the oil viscosity (Not HTHS), filter, temperature, and wear in the engine itself. The gauge will not show the minimum oil film thickness or the actually viscosity of the oil under mechanical pressure and cyclic loads in areas such as rings, bearings, cam, etc.


Good to note that engines have wildly differing operational loadings and such going on in a variety of temps and varying conditions.

I would imagine that a rod bearing experiences a very different operational loading than a cam bearing does...

 

[GatorJoe]

Our Ford in my sig needed all 3 timing chains replaced around 170k mi. Wasn't happy but bit the bullet and had it done. Have put on 35k mi since. Will now drive it til it's belly up.

 

[CATERHAM]

Originally Posted By: Brent_G
Originally Posted By: CATERHAM

I hear this type of odd contradictory statement from time to time from drivers that don't know how to properly read and interpret an OP gauge assuming the gauge is fully operational, some aren't. And/or they simply don't understand the concept of operational viscosity.

Oil pressure tells you what your operational viscosity is ever second an engine is running at all rpm levels, not the oil grade. An engine doesn't know what grade of oil is in the sump just what the actual viscosity is and that is predominately determined by the oil's temperature. With that info' one can make a more precise determination if you are in fact
running a light oil or heavy oil.



I understand however the OP gauge only shows part of the equation - does it show the temporary shear and viscosity loss in areas like the upper rings? KV40 and KV100 are important yes however do not take into effect HTHS.

Oil pressure is influenced by the oil viscosity (Not HTHS), filter, temperature, and wear in the engine itself. The gauge will not show the minimum oil film thickness or the actually viscosity of the oil under mechanical pressure and cyclic loads in areas such as rings, bearings, cam, etc.

You've got it backwards. HTHSV or bearing viscosity as it's sometime called, correlates very well with oil pressure, the KV100 spec' does not. Consequently OP does reflect the net effect of temporary oil shear, permanent oil shear, fuel dilution and of course oil temperature.
Why was explained at length in the following thread, titled HTHSV trumps KV100:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2276634&page=1

 

[demarpaint]

Originally Posted By: GatorJoe
Our Ford in my sig needed all 3 timing chains replaced around 170k mi. Wasn't happy but bit the bullet and had it done. Have put on 35k mi since. Will now drive it til it's belly up.


If you don't mind me asking what did that job set you back? Did you DIY or have a shop do it? Thanks.

 

[GatorJoe]

Originally Posted By: demarpaint
Originally Posted By: GatorJoe
Our Ford in my sig needed all 3 timing chains replaced around 170k mi. Wasn't happy but bit the bullet and had it done. Have put on 35k mi since. Will now drive it til it's belly up.


If you don't mind me asking what did that job set you back? Did you DIY or have a shop do it? Thanks.


Approximately $2,000 by a local shop. But that price included some hose replacements and t-stat housing changeout as well.