I've never been too sure about oil pressure.
I know we need it, of course, but I've only ever had one sort of bike with a gauge (an LE Velocette, . . . yes, I know - I've even had 2 of them over the years.) They come with handsome gauges, as someone must have liked making instrument panels.
It is 'supposed' to show 30psi at 30 mph in top gear, 'hot'. It doesn't. Cold, it shows loads more than that (as all things will); warm, it still shows more than enough; but after15 miles it shows 20psi at 30 mph in top, or the magic 30psi at 40mph - and always 10 psi minimum at tickover. The 10psi is very reasonable I think. The crank is in so-so shape or better, running on plain bronze bushed annular big ends. This on a wetsump engine which works hard to ensure any forward motion at all, with an inefficient sv engine - but offset by water cooling. That's on bog standard supermarket 20/50, which is my favourite ubiquitous slurp and has been for half a century in all my bikes.
But . . . is it right that a goodly proportion of whatever pressure there might be at a big end is as much a function of centrifugal forces on the crank journals as of the actual state of the bearings or of the oil pump? And is it right that flow is at least as critical as pressure? And does it matter what a gauge says if tapped into a line that is lightly stressed compared to a conrod bearing? I don't know and I don't worry unless nasty noises tell me different.
If I recall correctly, BMC A series car engines, which many of us grew up on, let the yellow oil pressure warning light flicker at about 7 psi - which was 'remedied' by increasing the tickover speed by about 50 or 100rpm so as to save the electricity for the bulb and mental wear and tear on the driver.
If I fitted a gauge to other bikes I'd probably panic, if I understood what the thing was really telling me that is . . . Luckily, I don't have them and they seem to work well, come rain come shine, like wortluck's.
