Mr. Fixit,

Thanks for the clarification of the tone of your response. No more needs be said about that as far as I'm concerned.

Obviously my perspecitive is different than yours. I look at it from and engineering solutions point of view. From my perspective, the crank and rod bearings are RELATIVELY easy to lubricate as they are what are referred to as "plane" bearings. The bearing and journal surfaces are (ideally) parallel, and the surface area is good sized (assuming proper sizing for anticipated loads). As long as sufficient lubricant is present the mechanical rotation of the mechanizm provides the action necessary to effect sufficient lubrication. Castrol has a commercial out that briefly shows the dynamic that occurs. It is called "hydrodynamic lubrication". What happens is that the rotational action draws the lubricant into the load zone of the bearing forming a wedge of lubricant to support the load (using a phenomenon know as laminar flow). This all assumes that clearances are proper, surface area is sufficient for the application, and a clean, adequate supply of the proper viscosity lubricant is available.

Within the context described, the purpose of the pump is to deliver that adequate supply (flow). The pressure reading is a result of the system restrictions (intended or not, they exist to some level depending on the system). Pressure is secondary to flow, and, as stated in the initial post, can be useful as a "diagnostic" tool to verify system operation. As your first post implied, the pressure sensor needs to be in the correct location to give a valid reading (apparently The Butcher had a problem with that as well). Where you and I agree here is, enough pressure is enough. The "more is better" syndrome has consequences as you indicated. It also can do harm to the lubricant.

When making reference to gear boxes, I had the bearings in mind more than the gears. Gear boxes, as I'm sure you are aware, but others may not be, contain plane bearings (similar to the crank and rod bearings) as well as ball, roller, and needle (very similar to roller in function). Of these, because of surface area, the plane bearing is relatively easy to lubricate. The rolling element bearings have a higher load carrying capacity due to metallurgy, but at any given point have less surface area contact, thus higher loads at point of pressure. As a result, while a plane bearing relies most on viscosity to provide adequate lubricant film, rolling element bearings will usually require the assist of an anti-wear additive (known by a variety of terminologies) particularly at pressure spikes.

Gear teeth are another matter still. Spur gears are the easiest to lubricate and at each tooth interface rely in hydrodynamic films. The most difficult are hypoid gears, (again for those who might read this that are less familiar with this terminology) the typical rear end style of gear (not typically applicable to FWD BTW). The high angle of incidence at the gear teeth interface has almost entirely wiping action rather than the rolling action of a spur gear. This regime requires "extreme pressure" additives to protect the teeth from wear (sulphur phosphorous is most common and imparts that lovely ? smell to EP gear lubes) as viscosity alone won't get the job done.

As with determining the tone of someone's post, writing a meaningful response to a technical issue can be difficult to do, especially briefly, due to the vast number of variable factors. Hope I haven't put everyone to sleep on this one.