Originally Posted By: Jeeplander
Hey guys Still got the same problem, no better. I have been doing some basic reading on syn. oil. If I switch over to Syn oil. would this help me in keeping a higher idle oil psi???? I'm new to this idea.
A synthetic will typically change less over the same span of temp. The difference is less between the hot and not so hot visc's. It's still sizable and while I've noted the differences in hot pressure indications, it's not all that simple.
The simple end of it is you can go up in visc and you will probably see higher hot idle pressures. A synthetic would reduce the time that you came off relief compared to a conventional of the same visc. Working that view around, it might come off relief at the same point where a conventional of lower visc did ...at the same time/temp.
..but you're kinda steering with a rudder with varied fixed positions. You can't just dial up your visc .5cSt at a time. I guess you can if you want to go through a battery of blending higher visc fluids into some baseline oil ..shift the mix up a tick at a time.
I'm sure someone here has recommended a used oil analysis. If you see Pb in the range of 100ppm, then I'd say you need to go back to the rebuilder and have a talk.
Edit: I haven't looked back to see if I already mentioned this, but I saw this in a 4.0. The Cherokee came in with a lifter ticking. The pressure was verified to be low. The remedy was to replace the pump with a high volume pump. It worked for a bit, but the pressure tanked. This was, like yours, a relatively abrupt onset of the condition. No rumbling ..no consumption ..it just happened. I never found the outcome of the vehicle, but I speculated that some oil gallery plug or restrictor may have failed ..like whatever meters it to the timing chain.
That was just my imagination back filling for a cause that would fit the symptoms. I would suspect if this was the case with yours, you probably would not have the relatively normal pressure that you do, but who knows?
