I was driving the other day in very hot weather here and noticed that my oil pressure gauge was reading right at the end of the red zone (although the idiot lights were not on). I checked my oil level at the next stop, though, and it was at normal max. level on the dipstick. Iām curious as to how the increments shown on the oil pressure gauge (face lift 4.0s) relate to actual PSI. I have heard that standard āacceptableā for oil pressure in all cars is 10 PSI per 1,000 RPMs of engine speed.
Later that night, when temps had dropped outside considerably, my gauge read in the usual range once again. All I can think is that perhaps itās getting time to change my pressure sender unit (?) With very hot weather (and hot/thinned oil - Iāve been running 10-30 generic synthetic) it inaccurately reads low, perhaps (btw, this is the ātrueā, OEM type of sender)? Superblue has almost 90K miles on her now, so maybe thatās due ā¦ (?) The only other possibility I can think of is that maybe the PO had disconnected/bypassed the oil cooler system for some reason.
My barrel oil gauge on my 88 almost always reads around 50.
I have installed my own oil gauge, with electric sender. When cold, I get 70 at idle. When warm, I get 25-40 at idle. While driving, with some rpm, usually around 40-60.
Thanks guys, Iāll try that then. btw, back to my original question, so if the oil gauge is, e.g., reading ā1ā then how many PSI is that (unless the gauge is blinky)? 10 PSI?
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
7
No idea. Whatās important, though, is that itās reading nonzero. And itās reading pretty much what itās always read, no dramatic changes.
btw, in light of my new 5.3 finally on its way here from PA, I decided to go to the old JLers website earlier tonight and look around for your XJS book. Found it. Funny thing is I started to print the whole thing off for the second time - all 730+ pages (double-sided THIS time, though, to save paper) - when I noticed, fortunately in time, that you mention in the preface that the Book is also on the Nine Lives CD. I guess I had forgotten about that inclusion. Phew! That saved me a chitload of copy paper and toner! That Book is really a major labor of love, btw ā¦ How did you ever find the time to write it? You are to be applauded heartily for putting it together, dude ā¦
btw, it is now a little over 10 years since you last updated the Book. Do you see any reason to do so again anytime soon, e.g. anything new, changed, discovered, etc. about the 5.3s since 2009?
My 94 4.0 coupes oil pressure gage was all over the place. When I did the coolant system I replaced the op can with a sender which was part of the TSB.
Now the gage is dead center under all conditions using 20/50 Dino oil.
Gordon
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
10
I have literally thousands of notes and emails saved, intending to make additional edits to the Book. Just donāt seem to get around to it any more. I started doing some perhaps a year ago, but didnāt keep at it long enough to justify a new release.
If and when I do issue a new release, itāll be in LibreOffice document format. Iād like to convert the whole pickinā thing into HTML as a web site with a few hundred pages (and far more photos!), but itās just too much work. I also plan to purge quite a bit of stuff from it thatās either not particularly helpful or just plain wrong. Simply editing the outdated information ā including dead links ā would be a serious undertaking.
So I run Mobil-1 20-50 and have put in some instruments to check temps. Cold the oil pressure is past the 4 (40psi?) and at 80mph on Cruise Control the pressure slowly drops just over the 2 hash mark, this is with the RPM at 2800, it takes about 30 miles at this speed in 90F weather for the oil temps to stabilize. The hot oil is about 230 and the pressure is just above the 2 mark. When I get off the interstate the pressure drops to just above the red at idle. Hot around town it stays below the 2 mark. This is with 230k on it the last 100k by me.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
13
Iām retired, have plenty of money and time. Itās inclination I lack. How do you crowdfund that?
I checked my oil level at the next stop, though, and it was at normal max. level on the dipstick. 
Iām curious as to how the increments shown on the oil pressure gauge (face lift 4.0s) relate to actual PSI. I have heard that standard āacceptableā for oil pressure in all cars is 10 PSI per 1,000 RPMs of engine speed.
Funny thing is I started to print the whole thing off for the second time - all 730+ pages (double-sided THIS time, though, to save paper) - when I noticed, fortunately in time, that you mention in the preface that the Book is also on the Nine Lives CD. I guess I had forgotten about that inclusion. Phew! 
