Oil Handbook - good read
 

Hi,

Almost since I bought our 2003 Prius, I have been fascinated by Prius transaxle oil. The NHW11 model used Type T-IV but the subsequent models used Type WS. I soon learned that changing the transmission oil significantly reduced cold temperature mechanical drag but I also learned Amsoil ATF was not the right answer. Currently, I'm using Type WS because as Type T-IV wears, its viscosity approaches that of Type WS. But I just finished reading a handbook that explains what has been going on:

The Practical Handbook of Machinery Lubrication, 3d Edition, Llyod O. (Tex) Leugner, Noria Publishing, 1328 East 43rd Court, Tulsa, OK 74105, $70+shipping

Tex provides a combination of theory and practical knowledge about lubrication without the sales malarkey found at different lubrication company web sites. Early on, he describes the three forms of lubrication: (1) boundary layer; (2) hydrodynamic, and; (3) elastohydrodynamic. Boundary layer is the typical lubrication film between the surface imperfections. But Tex goes on to discuss in depth the various solid coatings such a molybdenum, boron nitride and teflon. For example, suspended in the oil they are nearly useless but applied as a surface treatment before assembly, they can provide valuable protection during start-up.

Hydrodynamic refers to how as the velocity differences between moving parts increase, the oil creates high pressures to keep the parts from rubbing. The oil literally suspends the moving parts. But Tex also discusses the start-up wear that happens until the parts actually reach operating speed and mitigation systems such as oil pressure before load. This is how our Prius engines start with extended spin-up before the engine begins feeding fuel.

Elastohydrodynamic is new to me but at high pressures and speeds, the oil behaves as a solid, nearly perfect separator of moving parts. The oil viscosity changes but becomes a very efficient, very low friction surface insulating the two parts. For years, I'd noticed that as NHW11 speeds approached 65 mph, the vehicle efficiency improved even more than engine efficiency would dictate ... a 'sweet spot' at 65 mph. It may be we are seeing parts of the car operating in this most efficient, low mechanical drag region.

One of the lessons learned about Amsoil ATF is it 'eats yellow metal' and in particular, the copper measurements went rapidly too high. I caught it and switched to Type WS. However, Tex speaks about a copper test, the right answer when looking at any alternative lubricant for the NHW11 transaxle.

The last bit of the puzzle came from Tex explaining how polymers are added to base oil to extend the viscosity and that the base oil does not 'wear out.' However, these viscosity range improving, polymers are subject to 'shear down.' This explains how the Type T-IV approaches Type WS viscosity over time. In fact, Tex points out that oil doesn't wear as much as the additives are exhausted and it gets loaded with wear material. This certainly is consistent with the oil testing results.

At $70, this handbook is a little more expensive than popular books but the knowledge it provides, the insights, makes it well worth it to the curious. It is free from marketing FUD making it a useful guide for any technician or engineer who really wants to understand lubrication.

Bob Wilson

bobistheoilguy
 

There's as much unsubstantiated opinion floating around at Bob's as there is anywhere.

I had enjoyed Bob's site several years ago but The Practical Handbook of Machinery Lubrication has no 'soft sell' contents and covers the subject matter in more detail. It is a vendor independent, experience based, study and report that looks at lubrication in depth. For example, the introduction:
In contrast, Bob's looks pretty much just at engine oil and no real look at industrial lubrication. IMHO, private vehicle operation is a big market but not very conducive to controlled studies that compare A to B to A.

The author, Tex, also excoriates 'penny wise' procurement and management decisions that buy cheap lubricants, extended change intervals, absence of testing only to pay with equipment failures and production losses. At work I'm having to deal with a procurement department that is pulling the same sh*t. When they screw up and order something that doesn't meet the customer requirements ... they try to force engineering to change the requirements to meet what they bought. Only a fool tries to trick Mother Nature. <grumble>

There is more to lubrication than what Bob's covers ... if you're curious.

Bob Wilson

Frank -

Arghhhhhh, and I thought they were the bee's knees.

CarloSW2

Sure wish that was true. IMHO the place is full of what I call "recreational oil changers"- boys who actually think they are doing their engines a favor with excessive oil changing, and excessive expenditures on oil and oil related products.

Amen to that brother!

They keep citing brands without a lick of facts and data. Nothing!

Once upon a time there was a web site that was testing different engine oils, not very well, but at least they were performing oil analysis. Yet you could never tell what the heck the ICE usage profile was. . .

Please understand I'm more interested in transmissions and differentials (where they exist) than engines. What a joke ... Fool and money, soon parted.

Bob Wilson

I have been there at bobs site. I agree with you.

As if all engines are the same..

what would bob do with a 100psi trochoid oil system with 4 relief valves in an all aluminum liquid cooled boxer engine...

the real answer? anything you want.

the polymer stuff has been a nuisance as well as a blessing, I fall for the latest and greatest all the time. My latest is castrol edge, expensive, and it does not like to stay behind my new cam seal..but..everything else is absolutely fantastic...that is probably not on bobs site either. :rolleyes:

...from what I've "seen & read" the criteria for one oil being "...better..." than another has been (IMHO) either:

(a) technical hype,
(b) marketing hype,
(c) colorful hype, or...
(d) today's 'sale' hype.

...detect a "trend" here?