Oil related question

[F250HIGHBOY77]

Seeing as I did not trust the fella I got my 97 from I didn't want to take any chances on the so called oil change that "he just did". I got a Motorcraft filter for under $10 at my local Oreilly pats store along with some 10w30 Rottella. On my trip home from work after doing the oil change the darn thing pulled the big hill much easier and felt like it had more power than it did before. I then gunned the loud pedal and she just took off flying! Any thoughts on why it would run that much better?????

[351fifty]

Full synthetic? And the obvious answer is why bud

[F250HIGHBOY77]

No, just dino oil. Love how it ran going home but I am stumped as to why it's running better. The oild oil seemed kinda thick coming out so it makes me think he put in some thick *** oil???

[351fifty]

Or old *** oil, prolly never got changed, I change mine so often I never noticed tho, had oil and trans flushed as soon as I bought it

[jesilvas]

Because it's an HEUI system that runs the motor so oil is very important.

[madpogue]

Better oil, better hydraulic action, better performance.

[bucwheat]

I notice I get better fuel mileage with a new oil change too.

[99' Powerstroke]

The only thing I can think of is that the 10W30 you put in is thinner than the 15W40 that was most likely in there, so it's easier to pump the thinner oil through the engine.

[madpogue]

It's the hydraulics, not the lubrication.

[99' Powerstroke]

So the oil that was supposedly changed by the previous owner really was OLD?