What are your thoughts on the role viscosity plays in VVT engagement? It has been said that many modern engines have so many critical parts relying on oil viscosity. Some have even seen 05+ Honda's not have vtec engage because of an oil weight change.
Viscosity and VVT Engagement
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My thoughts are that it can't matter that much due to the far greater impact temperature has on viscosity.
Assuming we are talking about VCT as well as VVT:
- Ford's Coyote
- Chrysler's HEMI
- BMW's M-engines
All use the same VCT systems across engines with wildly different viscosity spec's.
Assuming we are talking about VCT as well as VVT:
- Ford's Coyote
- Chrysler's HEMI
- BMW's M-engines
All use the same VCT systems across engines with wildly different viscosity spec's.
I know Chrysler engines are ///very/// picky when it comes to their systems and oil used
The viscosity difference between a cold start at -F temperatures and operating temperatures is greater than the difference between a thinner and thicker grade of oil.
I ran 30 and 40 grades in my F150 spec'd for 5w20 and it was fine with no loss of power or mpg.
I ran 30 and 40 grades in my F150 spec'd for 5w20 and it was fine with no loss of power or mpg.
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Originally Posted by SnowDrifter
I know Chrysler engines are ///very/// picky when it comes to their systems and oil used
No they aren't. Literally the same system in the 5.7 that spec's 5w-20 is used in the 6.4L that spec's 0w-40.
They do however, use an oil pressure sensor to extrapolate viscosity based on oil temp and if it gets out of range, it can trigger a CEL. Former user Clevy was able to make his 5.7L do it on 0w-40 when it was -35C. Otherwise, it never came up.
I know Chrysler engines are ///very/// picky when it comes to their systems and oil used
No they aren't. Literally the same system in the 5.7 that spec's 5w-20 is used in the 6.4L that spec's 0w-40.
They do however, use an oil pressure sensor to extrapolate viscosity based on oil temp and if it gets out of range, it can trigger a CEL. Former user Clevy was able to make his 5.7L do it on 0w-40 when it was -35C. Otherwise, it never came up.
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Not directed at your question Pim Tac. Generally speaking for those that say there is a downside...
How would you be able to tell the difference?
How would you be able to tell the difference?
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Originally Posted by PimTac
Would there be a situation where the mechanism would work but not optimally?
Likely depends on the mechanism, the operation of which varies significantly between designs. My understanding is a few of them are locked out below a specific temperature to allow the oil to thin a bit. This is at points where viscosity is measured in thousands of cP, not the comparatively minuscule difference between grades of the same W rating at higher temps.
Would there be a situation where the mechanism would work but not optimally?
Likely depends on the mechanism, the operation of which varies significantly between designs. My understanding is a few of them are locked out below a specific temperature to allow the oil to thin a bit. This is at points where viscosity is measured in thousands of cP, not the comparatively minuscule difference between grades of the same W rating at higher temps.
It's controlled by the ECM or PCM so it probably doesn't come into play until the engine is warm and in closed loop.
There is a range that is allowable even though a particular oil is spec'ed because no 2 oils are the exact same CST value both cold and at operating temperature and they have to allow for things like fuel dilution, shearing and thickening over the course of an OCI. There's too many variables for them to hard code an exact number so they will use some sort of method to compensate as the oil changes due to the factors I listed. Such things as oil pressure, oil temperature etc.
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Originally Posted by SnowDrifter
I know Chrysler engines are ///very/// picky when it comes to their systems and oil used
That's news to me.
I know Chrysler engines are ///very/// picky when it comes to their systems and oil used
That's news to me.
Originally Posted by demarpaint
Originally Posted by SnowDrifter
I know Chrysler engines are ///very/// picky when it comes to their systems and oil used
That's news to me.
My 2012 RAM 1500 5.7 with 5W30 in it would go into 4cly mode 3 blocks from my house at 25°. The MDS didn't care about the 5W30 instead of 5W20.
Originally Posted by SnowDrifter
I know Chrysler engines are ///very/// picky when it comes to their systems and oil used
That's news to me.
My 2012 RAM 1500 5.7 with 5W30 in it would go into 4cly mode 3 blocks from my house at 25°. The MDS didn't care about the 5W30 instead of 5W20.
The fact that engine families are offered overseas with differing oil allowances for viscosity yet only a single accepted viscosity in the US tells me that it doesn't matter that much.
I consider spec'd viscosity to be important.
Today, I changed out GTX HM 5W20 (a surprisingly thin 5W20) for Pennzoil Platinum 0w20.
buster, I am sure you heard about the recall of 1.5L CRV's.
There you go.
Today, I changed out GTX HM 5W20 (a surprisingly thin 5W20) for Pennzoil Platinum 0w20.
buster, I am sure you heard about the recall of 1.5L CRV's.
There you go.
For the control to work between Arizona and Alaska, they would likely have to use some sort of feedback from sensor reading (viscosity, pressure, etc), and when you have that, you don't need to worry too much between oil close enough (i.e. 5w and 10w).
Kestas
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I had a 98 Ford ZX2 where the VCT faulted when i changed the oil with 20W-50. Problem went away when I swapped the recommended 5w30 back in.
Originally Posted by Direct_Rejection
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buster, I am sure you heard about the recall of 1.5L CRV's.
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Do tell! I for one am not familiar. Got a link?
edit: Or heavy fuel dilution?
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buster, I am sure you heard about the recall of 1.5L CRV's.
--
Do tell! I for one am not familiar. Got a link?
edit: Or heavy fuel dilution?
Originally Posted by buster
What are your thoughts on the role viscosity plays in VVT engagement? It has been said that many modern engines have so many critical parts relying on oil viscosity. Some have even seen 05+ Honda's not have vtec engage because of an oil weight change.
Funny, as one of Honda's papers on lower than 20 grade viscosity (one of those scary science type papers) says that in going thinner they have to be cautious that hydraulically operated systems function reliably with the typically lower oil pressures that arise.
What are your thoughts on the role viscosity plays in VVT engagement? It has been said that many modern engines have so many critical parts relying on oil viscosity. Some have even seen 05+ Honda's not have vtec engage because of an oil weight change.
Funny, as one of Honda's papers on lower than 20 grade viscosity (one of those scary science type papers) says that in going thinner they have to be cautious that hydraulically operated systems function reliably with the typically lower oil pressures that arise.
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