I guess I'm just naturally restless when it comes to oil and noises, so after reading
this blog on everything anyone could ever ask about oil, I drained the 15W40 with 2K miles and poured in a pint of MMO and filled it with Penz 10W40 high mileage. I don't care for HM additives but it is seeping a little around the rear main seal. Not enough to leave spots but enough to stay wet. Another reason I went with Pennzoil high mileage is because the blog also rates it very high. But hell, I don't know what's good anymore. Years ago I ran nothing but Castrol GTX but oils aren't like they used to be.
It's probably my imagination but I'd almost swear it runs smoother now.
Oil pressure dropped a little but still just a little over 30 at 700 hot and a between 45-50 hot at 2500RPM.
My reason for using 15W40 in the first place was because I bought the truck in the summer and knew I would be pulling a loaded trailer 550 miles with it very soon. Talk about a leap of faith! The guy I bought it from only drove it once in a while to keep the battery up. It had the look, feel and smell of something that hadn't been used in a long time, and I had put maybe 200 miles on it before time came to hit the interstate for a 9 hour drive. The truck and a tandem axle trailer were loaded and it ran great. Never missed a beat - or a gas station.
I have a question about the Seafoam. Should that be added during the oil change or shortly before? It's pretty watery and looks like a solvent. I've used it for years in the fuel but never in a crankcase.
Thanks for the help!
R