oil viscosity to protect plastic from rubbing metal

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Will thick oil protect the plastic chain guides from the metal chains better than a thin oil such as say 5w20 ?

A timing chain covered with heavier oil seems like would cause less wear on the plastic guides or anything plastic in contact with the timing chain ???

Any metal on plastic wear studies
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I would think lubricity would be a quality independent from viscosity.

Reducing friction seems like the goal...and this can be accomplished in ways that even a thin oil can accommodate.
 
Nothing you can do. The TC will eat the guides over time. Some syn oils will soften the polymer and end their life fast. Some will go 200K.
This is what I am a proponent of DRY timing systems on DOHC motors.

I know, I lost a timing system on my BMW M Roadster (vanos) due to improper oil. (according to BMW tech) I bought the car used and didn't have its OC history.
 
We do know that 30 viscosity oil is about the ideal viscosity for chains of all sorts. Thinner oils tend not to have the film thickness and therefore the ability to protect the chain against common particulate related wear. We also know that certain engines, such as the Ford Modular engine achieve exceptionally long life on 30 or even 40 viscosity oils. There are multiple reasons for this. However, chain and guide wear are chief among them.

Conversely, we have a wealth of data showing that extended oil change intervals, coupled with ultra thin oils increase chain wear, often requiring replacement inside the warranty period.

Either GM forgot how to make engines or the thin oils and extended drain intervals play a role. Strange that more viscous oil and more frequent changes fix the problem..... AND, not only on the GM and Ford vehicles, but the Prius also.

http://www.equinoxforum.net/31-engine-drivetrain/6533-balancing-chain-service-advisory.html
 
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Originally Posted By: HerrStig
Sounds like a design defect to me.


Correct, manufacturers who choose to use particular oils need to engineer properly for those oils.
 
If thicker oils promote hydrodynamic lubrication, which I understand they do, and this eliminates contact, which I understand it does, then it wont matter what the non-contacting surfaces are made of. Thicker oil will be better for all materials.

If there is contact then all that tribofilm jazz comes into play, it gets more complicated and the materials become relevent, but you want to avoid that.
 
Originally Posted By: Cujet
We do know that 30 viscosity oil is about the ideal viscosity for chains of all sorts. Thinner oils tend not to have the film thickness and therefore the ability to protect the chain against common particulate related wear. We also know that certain engines, such as the Ford Modular engine achieve exceptionally long life on 30 or even 40 viscosity oils. There are multiple reasons for this. However, chain and guide wear are chief among them.


^^^ This is interesting to read. ^^^
 
Originally Posted By: Linctex
Originally Posted By: Cujet
We do know that 30 viscosity oil is about the ideal viscosity for chains of all sorts. Thinner oils tend not to have the film thickness and therefore the ability to protect the chain against common particulate related wear. We also know that certain engines, such as the Ford Modular engine achieve exceptionally long life on 30 or even 40 viscosity oils. There are multiple reasons for this. However, chain and guide wear are chief among them.


^^^ This is interesting to read. ^^^


I was going to say, arent there lots in the wild that made very high mileage on 20wt?

I can think of a few delivery trucks in ultra severe service in the Caribbean that are liking 5w-20 havoline in a area where 100k odometer miles is more like 250-300k in the US.
 
Originally Posted By: ARCOgraphite
Nothing you can do. The TC will eat the guides over time. Some syn oils will soften the polymer and end their life fast. Some will go 200K.
This is what I am a proponent of DRY timing systems on DOHC motors.

I know, I lost a timing system on my BMW M Roadster (vanos) due to improper oil. (according to BMW tech) I bought the car used and didn't have its OC history.


Synthetic softening the plastic ?
 
I'd guess that the tribofilm jazz is mostly optimised for metal=metal contacting surfaces, though I don't know this for fact.

IF this is true, it suggest that the general superiority of thicker oils in reducing wear will be relatively greater for plastic surfaces, since the backup / second line of defence is likely to be less effective.
 
Originally Posted By: JHZR2


I was going to say, arent there lots in the wild that made very high mileage on 20wt?

I can think of a few delivery trucks in ultra severe service in the Caribbean that are liking 5w-20 havoline in a area where 100k odometer miles is more like 250-300k in the US.


Yes, there are plenty of high mile engines operated on 5W-20. There are fewer ultra high mile engines operated on the thinner oils though. Quite typically, the 500K and up club use a higher viscosity oil. Clearly the Ford Modular engines, many GM engines and certain Toyota engines last a very long time without trouble, on a somewhat higher viscosity synthetic. Consider the Crown Vic and Town Cars with 500K. Nearly all of them use 10W-30 or 10W-40 to achieve that. The ones with 900K miles all use the thicker oil. The 5.4L powered "million mile van" used 10W-40 to achieve 1.3M miles.
 
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