I am not disagreeing with the fact, that both gauges are a big help but, do they really tell you what is happening to the bearings, rings and cylinders?
Agreed...the gauges are measuring sump temperature and the pressure in the main oil gallery in the engine.
As I've stated previously, from that main gallery, oil passes through :
* Main bearings (turning at crank speed)
* Cam bearings (turning at half speed), and speed is one of the key design parameters in the lubrication regime of bearings.
* Oil squirters (generally multiple), which depending on their design, may be measuring kinematic viscosity (long pipes), or density (orifices)
* Rod Bearings...
(Go back to the bearing tutorials earlier in the thread, and see the difference in rotational speed has on lubrication.)
All of these items are in parallel (bar the rod bearings), so Caterham's OP gauge is measuring the resistance to flow across all of them, as an average. So asserting that each of these points is lubricated adequately by having pressure is false, it's a real good guess, I guess.
The sump temperature is the average of the temperature rises across each of these areas.
Bearings have measured and calculated temperature rises of 10s of degrees Celsius. Caterham has refuted that as "not feeling right" in the past, but it's fact.
It doesn't "feel" right to a person watching a temperature gauge, as the sump temp is the average of bearing temperature rises (tens of degrees), piston squirter temperature rises (not much to some depending on design), and chain squirters (not much rise),and oil pump bypass temperature rise (should not happen, as I agree it's wasted power, and unnecessary heat). Sump temp doesn't tell you exactly what is going on in any of the bearings, but I agree, you can gain a "feeling" that things are generally good, or turning to whoop...It's not a scientific, empiracle proof that all is good.
Now getting back to the rod bearings.
They are fed oil from oil that's already been through the crank bearings, have picked up heat (aforementioned tens of degrees C), lost pressure, lost viscosity, and reallyhave no direct connection to the main gallery pressure gauge, nor have the operating temperature monitored as the rise is diluted by all of the other feeds back into the sump. Rod bearings are operated in a highly cyclic load pattern, which is difficult to design for anyway.
Main bearing viscometer may or may not reflect adequacy of lubrication in the rod bearings.
, I think that the hot, atomised oil being flung out of rod bearings, being first contact with piston blowby gasses is probably the most likely place for varnish to be created in an engine. Hypothesis that I'm working on at present.
Though from your post, I'm thinking it is 
Yes, I'm very fond of the "Nectar of the Gods" M1 0w-40, which I've run in many vehicles/engines, including a number of high-mileage Windsor's. It is my oil of choice for that application and many others.
The Windsor and the modular have a difference between them that Trav touched-on, though not in the context of those engine families.
When you look at the bottom-end of a Modular, it has a deep-skirted block with multi-bolt (and side-bolt) main caps. Things aren't moving around on you with this setup. It also has a gyrator style oil pump, which moves a lot more oil, and at a very high pressure.
When you look at the bottom-end of a Windsor, you have your typical thin-wall cast non-skirted 2-bolt main lightweight V8. Things ARE moving around on you with this setup. The block flexes, the caps move....etc.
When you start to turn up the wick on these two engine families, that difference with respect to bottom-end rigidity is relevant. And may not be something you are going to see on an oil pressure gauge. This makes suggestions like Trav's (and one I echo) which is to start with an oil like M1 0w-40 and see if your pressure is consistent, if your magnet stays clean, that you don't accrue excessive particulate in the filter, and that you don't have stand-outs in your UOA's SAFER than starting with something thin and working your way up. Because once damage happens, it isn't like you can just "take it back".
For a Windsor, M1 0w-40, being on the thin side of the 40-scale, is a bit heavier than Ford's recommendation of 10w-30, and, in my experience, has been shown to provide exceptional protection at higher than stock power levels.
Guys that run a blower, which heats that 5 quart sump even more, and often share the oil with the engine, usually run something even heavier, like 5w-50. But oil and coolant temperatures are also elevated in these applications, so this is a natural progression in terms of going heavier to account for that.
