During the summer, I would be running a 10w-30 in your high mileage Durango. Pick your brand. Might help that hot idle oil pressure.I've been feeding my 322,000 mile Dodge Durango a diet of 5W30 PYB conventional with a Wix filter for the past year in an attempt to clean as much sludge as I can. I noticed now that Wal-Mart doesn't stock it any longer, and after investigating, evidently it's being phased out.
So what's the go-to now for an insanely high mileage vehicle with some sludge/varnish?
I really, really don't want to get into a synthetic for obvious reasons. That being said, right now I seem to have zero oil consumption and very minor if any oil leaking. I've been running Pennzoil Plat in my other cars but am seriously considering going back to Mobil 1. Does Mobil 1 have anything that's good at cleaning that you'd feel comfortable dumping into a 322K vehicle? Or would you go for something else?
Just for reference, I have a mechanical oil PSI gauge and I'm seeing about 12 PSI at hot idle and about 45 PSI at hot cruise on the highway.