Re: 02 ford ranger 3.0 oil pressure prob.
I have a 2000 ford ranger with a 4.0 v-6 that has 18k that has the same problem on start up (Im located 30 miles above the arctic circle on the north west coast of alaska our summers top out in the 70's on a hot week), lately the tempratures been in the mid to high 40's after the engine heats up the oil light goes off and stays off till the engine cools off useing NAPA sae w10-40, I found that when useing sae 0-30 oil that the problem existed evein when plugged in over night during the winter it would start right up with no lifter sound, the dip stick read full and I thought it was sludge in the oil passage to the sending unit
a little shot of marvel mystery oil in the oil filler shortly before oil change I'd run the vehicle a short ways to knock off the funky brown gunk in the inside the filler cap and then the engine worked normally for awhile till it sludges up again, Im not so shure if oil grades produce any more sludge than others, the marveil treatment to de-sludge the crank case at oil change helps.
Its best to get a oil pressure reading on the engine oil pump first before assuming anything!
then go from there!