I'm now towards the end of the rinse phase with my '93 Roadmaster with 5.7 TBI engine and about 175,000 miles. I never thought I had sludge problems, but ran a bottle through just to ensure that everything was freed up as much as possible (especially the rings). Oil pressure on the highway had consistently been about 33-35 psi with 10W-30. Over the course of the clean and the rinse phase, pressure would fluctuate +/- 5 psi or so as has been reported here, so I wasn't concerned. Now, however, pressure (at 2,100 rpm) runs a consistent 45 psi with the same 10W-30. That's a 10 psi improvement, at the very least.
