Today I was at the Home Depot and figured I'd grab a few big jugs of oil to change the Gladiator and the XJ (both with a 4.0). Normally I use Mobil 1synthetic 10w30 with a Mopar MO-090 filter which I buy by the 12pks. My Gladiators 4.0 idled around 43 psi and my XJs usually idled really low around 18psi. Today I bought Pennzoil Platinum full synthetic 10w30 since they didn't have Mobil 1 and my truck is now idling at 58psi and my XJ at 40psi. 3 years owning that XJ I've never had oil readings like that, and ive used Castrol as a substitute in the past a couple times. Think I'll stick with this brand going forward. Happy with the pressures as now the XJ is more where it should have been all along. I just wanted to tell someone this because it makes me happy and everyone I know around here could care less about my jeeping and shop antics.
But we do care......and keeps us coming back for the next session
'81 CJ5 Base, 258 I6, MC2100, T176 4 spd, 300 TC, D30 Front NT, 3.31, 2-Piece AMC 20 rear NT, 3.31, 4" high arc spring lift
'84 Grand Wagoneer, 401 V8 (.030 over), MC2150 HA Comp, 727 auto, Selec-trac NP229, AMC 20 REAR - D44 FRONT - WT 3.31, 4" high arc spring lift
Rather be driving, than waiting to be modified
Somewhat related, I've been using amsoil z-rod 10w40 and after long highway runs my oil pressure would get scary low at idle. Dropped some napa 10w40 dino oil in it before a 1,000 mile trek back home and highway/idle pressures are much improved. One would think the oil rating describes actual viscosity at differing temps but there's something else at play here.
I will throw something out there.. that high idle oil pressure is wasted oil pressure that bleeds offand can actually cause more lubrication issues than good. Just an fyi. 58 at idle is way too high in my opinion especially if thats a HOT idle in drive
With my continious rear main seal leak.. I cant try other oils as its a waste of money.. but id like to try oils other than the walmart special. Maybe if the penzoil is on sale lol.
But i am curious now because i used to put castrol gtx or valvoline blend in ny 90. And my oil pressure was like 20 at idle after highway driving and 50-60 driving
And with walmart oil itll go below 10 sometimes which i hate and 45-50 driving.. . I didnt think much about brands of oil and viscosity at temps.
I know project farm on youtube tests oils for this. Ill have to look at his vids and see what he came up with.
1998 Jeep Grand Cherokee 5.9L Limited 215k
1998 Jeep Grand Cherokee 4.0 I6 laredo 394k
1990 Jeep Grand Wagoneer 151k
1976 Jeep J10.. 84 (in shambles/repairing)
Don't worry I've gotten the same feeling with a bunch of my posts and stuff.
I would be questioning the actual viscosity of the oils. Either Mobil 1 is lying or the other brands are lying. Something ain't right.
I also agree with candymancan--58 psi is WAY too much for a low-end torque engine. I highly doubt you're revving it to the moon; it's not a 8000+ rpm racing engine. Even if it does hit that kind of speed, it shouldn't be frequent enough to need that kind of pressure.
With great optimism comes great frustration from those who don't fabricate the bandwagon they jump on, as well as a responsibility to make sure the bandwagon is strong enough when others start jumping on it.