trench_fighter

i just bought an 92 laredo from my gma/gpa who drove it two three days out of the week and lack more than somewhat at knowing anything about car problems. it's got the 4.0 HO. it starts and drives fone w/o anything noticably wrong but sometimes i notice after it has reached op temp and im just cruising the oil press gauge is at 80psi when only a bit before it was at like 45-50. they said they ran 10w-30 in it but ofcourse then they think they ran 10w-40 too. could they have mixed the two and sometimes the pump sucks up the 40? or could i have something else the matter? i know that 40s way too much, i even think 10w-30s a bit high i figured i'd try 5w-30 for the next change seeing as most of my miles are highway and i've been told the 6cyls prefer lighter oil. oh and when my fan kicks on it's seems kinda louder than i think is normal, what could i look for with that too?

peep

The Hi pressure won't hurt ya. Most likely an erractic sending unit. Had a similar reading on our 95 ZJ. Sometimes the gauge would show maxed. Recently the sending unit failed, an internal rupture, found oil leaking out the wires of the sending unit. Removed sender and plugged with 1/8npt till new unit received. As wires are dangling and receiving no sending unit influence, the gauge reads maxed. Your 45-50psi when running at operating temp sounds just right, I would suspect the sending unit is failing when you see that maxed / high spike to 80. Check your plug connection. Perhaps access to a second mechanical gauge could be substituted to provide second set of readings for comparison?

peep

PS: 10w30 works for me, fresh filter with every change, change every 5000 to 7000 km. The Peep XJ is running over 536000 km on that regimen. The fan noise could be the fan clutch going south. Often accompanied by vibration.

trench_fighter

thanks for your help