One aspect of VCT operation

[229]

Knowledgeable comments are welcome.

Car manufacturers design VCT systems with small oil passages to keep oil pressure at a higher level than orthodox engines. A certain amount of flow volume needs to stay consistent once the closed-loop operation begins and the retard/advance function commences. These design parameters require a narrow range of oil thickness as opposed to traditional engines.

A cold start up produces the most wear in an engine. A thermostatically controlled engine should operate in a stable environment the majority of the time. If one increases oil thickness beyond recommended limits, one may affect the performance and augment the wear of the VCT system.

 

[ARCOgraphite]

In winter operation the warmup period may last the whole commute distance and a 5w20 oil may never dive below 60cst. Hydraulic VVT have problems - some manufacturers are looking at non hydraulic systems. Ford has implementsed some mechanical on the coyote and toyota is looking into electric motor cam phasing.

 

[ARCOgraphite]

Originally Posted By: 229
....
A cold start up produces the most wear in an engine. ....
I think this has been proved incorrect many times with very controlled university studies using and detecting atomically enhanced materials for real time analysis of wear. Full engine load causes the most wear by % over service life.

 

[daman]

Originally Posted By: ARCOgraphite
Originally Posted By: 229
....
A cold start up produces the most wear in an engine. ....
I think this has been proved incorrect many times with very controlled university studies using and detecting atomically enhanced materials for real time analysis of wear. Full engine load causes the most wear by % over service life.

And with todays thinner used oil's it's even less of a problem.(was that a Knowledgeable comment?

)


@OP do we need two threads on this subject?

 

[jmsjags]

Originally Posted By: ARCOgraphite
Originally Posted By: 229
....
A cold start up produces the most wear in an engine. ....
I think this has been proved incorrect many times with very controlled university studies using and detecting atomically enhanced materials for real time analysis of wear. Full engine load causes the most wear by % over service life.


by full engine load do you mean WOT runs?

 

[chubbs1]

So in other words don't use 0w40 if the vehicle is spec'd for 5w30? Does VI play a role? IN other words if one 5w30 has a VI of 150 and another 180, would that make any difference to the VCT operation?

 

[daman]

Originally Posted By: chubbs1
So in other words don't use 0w40 if the vehicle is spec'd for 5w30? Does VI play a role? IN other words if one 5w30 has a VI of 150 and another 180, would that make any difference to the VCT operation?

Haha i doubt it's that sensitive to viscosity a 0w40 IMO would be fine it usually shears down some anyway and being a syn it should flow just fine at start up.

IF there is a big concern here is there a big warning in the owners manual? does the sales man give you this warning before you buy the car?

 

[OVERKILL]

Originally Posted By: 229
Knowledgeable comments are welcome.

Car manufacturers design VCT systems with small oil passages to keep oil pressure at a higher level than orthodox engines. A certain amount of flow volume needs to stay consistent once the closed-loop operation begins and the retard/advance function commences. These design parameters require a narrow range of oil thickness as opposed to traditional engines.

A cold start up produces the most wear in an engine. A thermostatically controlled engine should operate in a stable environment the majority of the time. If one increases oil thickness beyond recommended limits, one may affect the performance and augment the wear of the VCT system.


BMW runs 5w30 and 10w60 in the same VCT systems depending on whether they are in an "M" car or not.

Ford recently recommended people run 10w40 in the trucks with VCT if they had noisy phasers. These trucks spec 5w20.

 

[OVERKILL]

And an excerpt from my reply to you in the other thread:

It is ALL relative to temperature. The viscosity on the bottle is but a given data point for a viscosity RANGE that defines an SAE grade.

If you go and use Widman's Visc calc and plug in the values for a few 5w30's and 0w40, you'll find that:

A). They aren't that far off (M1 0w40 is only 13.5cST at 100C versus 11cST for their 5w30, PP is 10.3cST)

B). A 10 degree difference in oil temperature (which gives us a nice example of the affect ambient temperatures plays on oil temperature) shows us:

M1 0w40 @ 90 degrees is 16.8cST
M1 5w30 @ 80 degrees is 17.4cST

So if you've got one guy living in Winnipeg and another in Florida, even if the guy in Florida is running the "incorrect" 0w40, he is still running the LIGHTER oil by virtue of higher oil temps.

 

[SteveSRT8]

I can only speak to Chrysler and their VVT/MDS setup, which is oil driven.

There has been much ado over the oil spec since 2004. It is complete bunk, as thousands of Hemi owners have discovered that all thicker oil does is change the operation very slightly, if at all.
20w, 30w, 40w, and even 50w work just fine.

And in case you didn't know it, startup wear is documented to not be the problem we were all lead to believe either!

 

[chubbs1]

Great info, this is why I love BITOG!

 

[mechtech2]

229-
Smaller passages do not increase oil pressure.
When cold, an engine with too thick oil with some VCT systems may not operate correctly until the engine warms up, and the oil thins out.
As to cold start up wear, it is attenuated by modern FI and engine management systems that start the engine fast and have less fuel dilution.
Start up wear the most wear? It could be on some and not on others.

 

[GMorg]

This start-up wear issue really depends on driving habits. Its like saying that breast cancer is a significant cause of death in people. Although that statement is true, it does not apply to men. Breast cancer occurs in men, but is not a significant cause of death in men.

Engines that are run hard, with heavy load, over long periods of time do not experience a large percentage of wear during start-up. Engines that are used for very short trips or in very cold weather spend their entire service in start-up mode. Nearly all of the wear on these engines would occur during start-up.

 

[Nickdfresh]

The weights of oil available commercially simply don't make much of an impact on the VCT system. Granted, I would never put 15w40 in a newer Ford and would use whatever the manufacturer recommends, but I believe there are still some police dept's that do without destroying the engines.

 

[229]

Techs have replaced thousands of cam phasers. Factory tells us that incorrect oil viscosity and filter shedding from non-OEM oil filters have caused the failures.

 

[SteveSRT8]

Sadly, the overwhelming majority of those are one brand. But let's not get sidetracked.

The huge increase in complexity to run these elaborate multi OHC and mega variable multi valve setups is seeming to come at a cost.

I'm not sure they are worth it.

 

[TFB1]

Originally Posted By: 229
Techs have replaced thousands of cam phasers. Factory tells us that incorrect oil viscosity and filter shedding from non-OEM oil filters have caused the failures.
So how do they determine if the incorrect viscosity oil was used or the cause was due to thick oil from short tripping???

 

[OVERKILL]

Originally Posted By: 229
Techs have replaced thousands of cam phasers. Factory tells us that incorrect oil viscosity and filter shedding from non-OEM oil filters have caused the failures.


I can believe the latter, but not the former due to the reasons myself and many others have mentioned.

A quick look at BMW specifying ranges from 5w30 to 10w60 for their VCT systems should clear that one up

I'm assuming the OCOD is the filter in question?

 

[cp3]

But would that not assume all VCT systems are created equal? Personally I don't feel that BMW's VCT immunity to different viscosity of oil means all systems are not sensitive to it. Could there not be different programming for an M car's VCT than there would be in a regular car to deal with the different viscosity?

I am curious about this but unfortunately have no answers.

 

[OVERKILL]

Originally Posted By: cp3
But would that not assume all VCT systems are created equal? Personally I don't feel that BMW's VCT immunity to different viscosity of oil means all systems are not sensitive to it. Could there not be different programming for an M car's VCT than there would be in a regular car to deal with the different viscosity?

I am curious about this but unfortunately have no answers.


Right, but they ALL have to be insensitive to viscosity, given the HUGE swings in viscosity due to ambient temps. An oil can go from 20,000cSt to 11cSt during the winter. That is a HUGE range, FAR greater than the 2 or so cSt we have between a 5w30 and 0w40.