Slippery Oil
- Thread starter Shel_B
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You mean, more slipperyer?
Are you asking about Friction modification (FM) properties?
If so, some boutique oils advertise improved FM properties, but I am not sure if there is a standardized test (or scale) to validate these claims.
If so, some boutique oils advertise improved FM properties, but I am not sure if there is a standardized test (or scale) to validate these claims.
There are two kinds of "slippery": Shear force friction and boundary contact friction. More friction happens when the parts are actually rubbing on each other vs. the pure shear forces in hydrodynamic lubrication. Viscosity and VIIs effect the shear force friction, and the AW/AF additives effect the boundary contact friction.
So yeah ... depending on the FMs, two oils of the same exact viscosity could have different levels of friction (aka "slipperiness").
So yeah ... depending on the FMs, two oils of the same exact viscosity could have different levels of friction (aka "slipperiness").
MolaKule
Staff member
Bananas are slippery too if you step on them.
I have never liked or used the term "slippery" because there is no unequivocal tribological definition for it. It is mostly used in marketing literature without any context or reference to friction, so I ignore it.
Tribology is one of these areas often described as the science of “rubbing and scrubbing”, its focus is on how moving surfaces interact with one another. Regardless of the sector they work in, something all tribologists are obsessed with is friction, the resistive force that acts parallel to surfaces, either to hold stationary objects in place (static friction) or to modify the friction between those surfaces that move (kinetic friction) via a lubricant.
By measuring the friction forces between materials, and incorporating them into mathematical models that have been developed and updated over decades, tribologists can glean a deep and sophisticated understanding of surfaces. In doing so, they can find ways to control the friction that acts on them. Every system with connected parts, be it engineered or biological, has been designed with friction in mind.
When I added Schaeffer Moly EP to my trucks oil that is the most slippery oil I have ever felt even when used. I think one of Shaeffers oil has the Moly EP already in the oil or its additives if you want a blended oil. Not sure but I would guess it is the Antimony in it.
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I found a post awhile back on BITOG, a user BOBISTHEOILGUY said to put a bit of oil between your two fingers. Grip a screw driver at the end only using those two fingers. Now try using Schaeffer oil between your two fingers. The screw driver fell out of my fingers much easier just as BOBISTHEOILGUY mentioned.
So if all things are held constant, and one oil (or any lubricant between two moving surfaces) caused a reduction in friction between the sliding surfaces, then it could be said that oil is more "slippery" than another - even though it's not really a "recognized tribology term". Saying "less fricion" implies "more slippery".
Lubricity is probably the better term. If you want to decrease friction, get the rings to transition into EHD sooner and for longer. Often it's not just about which oil can produce the lowest friction coefficient but which one can allow that friction manipulation to work on your favor. You can chase a friction coefficient in MTM or SRV, at whatever pressure and rotating speed, but it's meaningless if the engine never sees those conditions.
Fresh oil is the most slippery. That's all I need to know.
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This is REALLY useful: but only IF you are trying to affect how much finger pressure is required to hold, or not hold, a screwdriver between fingertips. B-)
Not necessarily. There's a lot of cases where the friction coefficient, at each lubrication regime, has gradually dropped the longer the oil is run.
Is the coefficient of friction even a “thing“ for any modern motor oil? I would think viscosity drag would be a much higher order effect than the difference between any of today’s motor oils.
There is surface friction when not in full hydrodynamic lubrication. When the asperities at the surfaces are rubbing on each other, AF/AW properties come into play and that can effect the friction level. There's a lot of boundry lubrication going on in an engine. I know that CeraTech reduces friction ... the Mustang guys use it in the Coyote to make the BBQ tick go away, which seems to be kicked off by the friction level between moving parts.
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"This test doesn't simulate engine operating conditions perfectly, but it will give us a lot of useful information."
Yes, such as what to avoid getting on your fingers while working on a car so you don't keep dropping screwdrivers
Or how much beating your skin is able to withstand from carcinogens in engine oils.Yes, such as what to avoid getting on your fingers while working on a car so you don't keep dropping screwdrivers
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