Here's what i know. Had a water neck rot issue with my ol '02 Ram, replaced it , and parts guy said factory recommends 195. I was running a 180. Truck ran killer, even though it had 280,000 miles. Put that 195 in, it about Fried my 5.9, going to Publix and back (1 mile each way), took it out, put in a 180, back to normal. I Have to side with RustyRatRod on this. Shoot, the Napa 195° is in the winder sill at the old house....reason I say this. I had a Very Accurate Temp Gauge on that truck, plus, a factory one. You could "see" the temp climbing, from a Cold Start, effectively " watchin" the T - stat open
