I just finished 2,560 miles of ARX cleaning on a well maintained, solid 1999 Jeep Cherokee 4.0l with 107k miles. I used Valvoline conventional and a Supertech filter. I am about 150 miles into the rinse phase with Blains Farm and Fleet conventional oil and a Purolator filter. Mr. Miller graciously reviewed the Blains oil MSDS for ARX compatibility.
After the cleaning phase oil change, my oil pressure gauge reads about 25+ lbs higher than normal. To confirm this, I turned the ignition to start which sets all of my gauges and idiot lights to on, but before engaging the starter. The dash oil pressure gauge reads about 25+ lbs with the motor still. This does not appear to have anything to do with a stuck oil pump relief valve which otherwise can cause high oil pressures. Also the effect of any blocked oil galleries would not appear at start time. The engine sounds fine, the oil looks OK, no oil level change at all.
The FAQ for Why do my engine lights come on states that the internal engine sensors (e.g., oil pressure sending unit) may be affected during the cleaning phase. My situation occurred shortly after beginning the rinse phase.
I opened my oil filter at the end of the clean phase and found only a dark, brownish coating on the paper element. It did not appear to be thick and heavily contaminated with sticky sludge nor was/are there any unusual oil starvation noises or tappet clatter. The old oil was a very, very dark brown, not pitch black like tar.
The ARX regimen for vehicles with over 100k miles recommends two rinse/clean cycles. I suppose I could remove the oil pressure sending unit and attempt to clean it out. This is an expensive, hard to reach, potentially fragile plastic/metal unit. If this is a rinse phase event that will fix itself, I will gladly defer risking the sending unit or worse, replace it only to have it get dirty again during the next clean/rinse cycle.
My shop manual states that the driveability risk for the sending unit is that a LOW reading will engage a limp home mode. Again my gauge reads higher than normal, not low.
Do my high oil pressure readings appear to be a rinse phase event that has happened to others before?
Is this likely to fix itself during the remainder of the rinse phase?
Will the next clean/rinse cycle be less likely to affect my oil pressure sending unit?
Thanks for your help!
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Pointsnplugs
1999 Jeep Cherokee 4.0l, 109k miles 2006 Jeep Liberty 3.7l, 47k miles
