It's not just the 203F factory thermostat to blame, but also the grille shutters. The HEMI is being run way too hot from the factory, and that coupled with fuel economy oil spells disaster as the oil polymerizes every time the engine is heat soaked and you turn it off. Since I did a grille shutter delete and switched to a 180F thermostat, the M1 FS 0W-40 is pretty clean at ~5000 (on the dipstick). Before it was already a brownish / bronze color at this point. These engines were never meant for 0/5W-20, due to questionable Q&A and manufacturing, let alone that kind of heat. Though something like M1 5W-30, PP 5W-30 (not PUP), Castrol EDGE or Magnatec (this one has esters in it), QSUD, or any 5W-30 motor oil that you can get at Walmart and doesn't easily shear down to a 5W-20 will serve anyone well that has a Gen. 3 HEMI and is running a 180F stat and did a grille shutter delete. At that point, there is no more need for expensive oils like Redline or even 0W-40. Also, PUP 0W-40 is inferior to M1 FS 0W-40. Marketing does wonders though. If you really want a though oil that's cheap, look no further than QSUD Euro 5W-40 available at Walmart for $18.97 per 5-quart jug. I bet it slaps the **** out of PUP 0W-40. These days it's API SP rated, and it's also the same oil recommended for the EcoDiesel. It's got Moly, Boron, and a Calcium-Magnesium detergent system, and plenty of ZDDP. And it's ACEA A3/B4, Porsche A40, BMW LL01, MS-10725, and MS-12999 certified. Judging from what it can do, it has ester in it. Esters are not expensive, the problem is that you have to have the right base oil combination to accommodate them. That's why Lubegard Bio-Tech doesn't work that well in every oil that's mixed with. Lucky for me (and I didn't know it at the time), M1 FS 0W-40 has esters in it, mostly to deal with soot and other issues. That's why M1 + Lubegard has worked so great for me. The M1 EP line doesn't have esters in it though. If you're cheap, Castrol Magnatec is another oil that has esters in it, that's why most people with crappy engines use it because it quiets them down.