I have a 2002 Mercury Sable. Lately, the oil light has been coming on intermittently. It does not stay lit solid, but instead flickers, especially when at a stop. Things have progressed, and now the engine is ticking when started cold. The ticking seems to diminish, or go away entirely when the car is driven a bit. I believe there is a problem with the oil pump, and that is causing the light to come on and lifters tick. The oil is full and is changed regularly. There are no leaks, but likely some consumption.
I've watched a lot of your videos over the years. I love your YouTube channel and content, but I did a search and could not find a video addressing this subject. Is this something I can fix myself, and if so, can you show me how to do it?
Thanks, Scotty!
-Robert D.
Stop driving it. Check pressure with a mechanical gauge. Low oil pressure can have other causes than the oil pump (worn bearings, sludge, blocked oil pickup screen, and more).
https://motoringjunction.com/tips-tricks/low-engine-oil-pressure/
As to the oil light not staying always on: it is normal behavior, and it shall not be interpreted in terms of the oil pressure situation not being dangerous enough.
Vehicles often have two oil sensors with different trigger settings, each able to trigger the oil light independently of each other: one only active under load (say, at about 2000 rpm, making sure that under load the oil pressure does not go below, say, 1.8 bar) - and totally inactive under all other rpms and conditions; and the other one being active when the engine is idling (or working with minimum load and rpm) and checking that under these conditions the oil pressure never gets below, say, 0.3 bar.
As one of the consequences of the way these sensors work, you may well have huge oil pressure problems, but at a certain time you may be getting no oil light, cause at that specific moment the conditions for the ECU to start checking the abovementioned sensors are not met. Practical conclusion (just like Chuck Tobias wrote): the very first occurrence of the oil light should give you enough reason to really start worrying, stop driving, and start investigating the root cause.
On some vehicles, the ECU may start blinking with the oil light, when the oil pressure is not just bad (although even "just bad" is imo dangerous enough), but when it goes absolutely and unacceptably bad.
Frankly, the most common reason for the oil light are not oil pressure problems, but rather oil pressure sensor problems (it is not uncommon for such sensors to go bad, and I even had both of my sensors go bad simultaneously). But since you mentioned ticking when starting cold, this is not your case - you are most probably having not a sensor problem, but real oil pressure issues. As to the possible causes thereof, Chuck Tobias mentioned most of them. It could also be blocked oil pressure regulator valve and/or blocked oil spraying nozzles inside the engine (especially, but not necessarily, if any oil additives (like leak-stops etc) have been used recently).
Checking the oil pressure with a mechanical gauge is relatively easy: I could do it myself. Same about dropping the oil pan and cleaning the oil pickup screen if you see that it is blocked. Same about the oil pressure reg valve. But for dealing with the oil pump I would need a mechanic, since diagnosing its wear status requires some fine measurements. And if the root cause proves to be general engine wear, I would just recommend getting another engine or saying goodbye to the car.
/IMHO disclaimer goes here/
