Reading old posts is getting me to the same conclusion but is it ok to be at the bottom of the spec? Would like to fix it right but don't want a needless repair either.

 

Per the mx manual oil specs 10W/30 is only recommended for max ambient temps of about 95 F. What have your local temps been? It gets much warmer under the hood for much of the year in many parts of the US. The lower viscosity oils have been recommended for years to boost the mfgs mileage averages.
.....

 

South Dakota so low to mid 90's is common during the summer. Both times the light flickered it was in the evening with cooler temps after parked about 20 minutes after a 15 minute drive. Thinking the pressure is just borderline minimum and that's why the warning light flickered. It went off right away at first start and then flickered on after a few seconds. It went off on its own again within 5 seconds, Just as I was getting ready to shut it off.

 

I would start with a Bosch oil filter and a 10w40 full synthetic oil change myself. I bought a Rover that the oil light would come on and stay on when cranked until I reved the motor up. Mobil 1 10w40 oil change with a Bosch oil filter fixed he issue for me.

 

I'm sure you've noticed there is a lot of info, often conflicting, here on oil and the proper choice.

One conflict being synthetic etc... reality: 1964 design flat tappet push rod V8 with notoriously "loose" tooling in mfg... Synthetic anything? Really?

Reality: Use an oil made for dirty old engines... Rotella T4 15w40 for $13/gallon at Wal-Mart does the job with lots of detergents and high zddp due to it being meant for diesel engine use. It cleans while you drive, literally. Change it every 3000 miles ish with a quality oil filter and you will be fine... Unless you are a Bay Em Vay driving oil snob. //sarc

 

Thank you, good advice from all. I have a case of 15w-40 at home for my diesels but never thought to use it in a Rover. Will give it a try and report back with the pressure numbers. Thinking if it gets above 10 psi at hot idle I'm ok. will also get an electronic gauge hooked up inside the cab.

 

I wanted something totally independent of the factory computer. Almost settled on the GlowShift but then found Auber Inst. Very happy with their stuff.

www.auberins.com/index.php?main_page=index&cPath=5_21

 

Changed to Rotella 15w-40 and Wix filter. Did not drop the pan or any internal inspection. Not sure why these results on 10w-30 vary from my original readings early in the week so noting the latest below. My gauge starts at 10 psi so best estimate on the accuracy below that.

10w-30 just before changing
Cold idle 45 psi, cold 2000 rpm 50 psi
Hot idle 7 psi, hot 2000 rpm 26 psi

15w-40 right after oil change (engine hot, oil just added)
Cold idle 20 psi, cold 2000 rpm 48 psi
Hot idle 9 psi, hot 2000 rpm 34 psi

Previous owner states he had occasional oil pressure light flicker (3-4 times) on hot start up ever since it was rebuilt in Oct 2015 so I'm probably no worse than it was at rebuild. I'm leaning toward running as is unless you all think that's a bad choice. I haven't called the rebuild shop yet. Feeling won't get far being the 2nd owner and 20k miles later. Opinions welcome.

 

34 PSI at 2000rpm hot is for sure low, look into it,, sufficient oil flow with reasonable oil pressure is a must if you want the engine to last,, is PO says light came on every now & then after rebuild its the sign of a bad rebuild to begin with,
Check the oil pump first, for crack or scoring of front cover, if bad then you found the problem,, if it checks out OK then problem could be as simple as a bad pickup tube O-ring or a complicated problem like, loose crank bearing clearances or camshaft bearing problems,, but either way don't neglect low oil pressure, you might be able to fix it with less cost now b4 something bad happens (if it has not happened yet) , but if you let it go knowing you don't have enough oil flow in critical parts of engine , then you should blame yourself for not taking care of it when you could have.
It's bad enough to buy a car & then find out it has a problem, but at least you found out it needs attention right away, good luck,

 

Here's an update for the archives. Too many posts with problems and no conclusions.

I replaced the front timing cover with a new one. Inspected a few rod and main bearings but in my opinion not that worn. Hot idle now 14 psi, hot 2,000 rpm 45 psi. That's nearly double what I had before. Using a $15 Equus manual pressure gauge so will look for an electronic gauge to compare accuracy and continuous monitoring from inside. Thanks for all the advice.