Moly and roller lifters........skidding???

[unDummy]

http://www.valvoline-technology.com/upload/dynamic/Diesel Engine Cam Galling.pdf

 

[JAG]

That study is very interesting, unDummy. It turns out my understanding of the situation was wrong. Reality is often more complex than our impression of it. I think I may post that link in the Passenger Car Engine Oil forum because it teaches us several things.

 

[1sttruck]

Good article, but more comparisons of viscosity vs base stock vs film thickness would have been nice. As I understand it (meaning that I might not :^) it reinforces the basic assumption that thicker oil films tend to produce better wear protection, and that the galling in this case is due to oil films being too thin. I don't see how that relates to moly and galling, unless moly somewhow reduces the thickness of oil films. The oil forming properties of the base oil can be modified but doing might suggest that you've removed one layer or protection, as if it's additive related then if the additive is reduced you've lost a primary defense against wear.

Does this help to possibly explain why some M1 formulations show high Fe ?

 

[1sttruck]

Thinking more about moly and galling.... moly may affect the 'SRR', sliding to rolling ratio, where undesireable ratios can result in galling. Since the galling is due to the film thickness being too low, the moly must be affecting the film thickness. The article seems to use a circular argument though, as galling is due to the film thiockness being too low, the film thickness is too low due the traction coefficient being too low, the traction coefficient is dependant upon the viscosity and pressure-viscosity coeffient, which results in a film too thin to prevent galling.

 

[1sttruck]

Another thought.... what we're really interested in is temperature vs pressure vs film thickness, a curve, but I guess breaking it donw into vicosity vs pressure-viscosity coefficient makes some models somehwere more useful.

 

[Black Bart]

I switched to Red Line 10w40 this spring in my 406 that has a custom grind Comp Cams roller with a rev kit.
In the past I was using M1 and Syntec with no problems in 6 years so stay tuned if it fails I will post it here.

 

[wileyE]

Many of the roller lifters and especially rockers failed from poor design, the easy way out was to blame the oil.

 

[jsharp]

I think Wiley has it right. The first time I heard this myth was many years ago from some of the local Harley crowd. A bunch not known for science, technology, or advanced engineering.

It then spread to other areas and here we still are...