RE: mopar oil =who makes it? mopar oil filter who make it? Plugs can i run plaitum champions
Most likely it's 5w-30, not 20. Oil bought in quarts is about $3 -- nothing special there. If you buy it in five-quart jugs, it'll run a bit less. 5w-30 Pennzoil Hi-Mileage is something like $12.70 for the jug. I buy three jugs at a time which gives me two oil changes and a bit to add, if needed. $35 is more like $5/qt. but the price probably included the filter at eight bucks or so. You'll find a regular debate here and on other forums about the "best" filter, "best" oil, etc. Your "best" bet is regular oil changes in the 3K to 6K mileage range using decent quality materials.
The 180 'stat won't add 15 dyno horsepower -- maybe three. I put a 180 in mine mostly 'cause the original was beginning to stick closed. Mopar filters are made by the lowest bidder at the time. Platinum plugs are not recommended in the Hemi. Colder plugs are for engines with boost (super- or turbo-charged) or chips. How many miles are on your new ride? It may be time for plugs -- 30K is the recommended interval, 40K-50K is probably OK. I put NGK 5306s in mine. Remember, there are sixteen plugs.
87 is "acceptable" 89 is preferred. 91 is OK, but a bit overkill on a stock motor. 93 is not recommended unless you're running a chip or boost. If the truck didn't have an owner's manual, you can download one at dodge.com. Very useful document for regular maintenance issues.
Depending on how deep your pockets are, power can be added... e-fan, aftermarket exhaust, and intake kits are not terribly expensive and cumulatively may add 30 hp and some torque. Serious power costs serious $$$.