Oil viscosity

Do you notice any subtle difference in how the truck runs in summer with the 5-30?

 

Yes, it is smoother, with less clacking, or valve chatter. I do not notice any difference in performance other than maybe very slightly less mpg’s.

 

In the old days, like in the 80s when Formula 1 was not so strict on rules and race teams had different engine tunes for qualifying vs race day, they would also play with the oil in the engine since the qualifying engine was practically a throw-away run at the absolute limit to achieve the poll.
Also, in Nascar, in the past they would run the engines as dry as possible before dry sump setups with the thinnest oil possible to make more power for qualifying. Thinner oil, and less of it, meant less parasitic drag on the crank. I vaguely remember an engine dyno chart i think Gibbs or somebody had leaked or they posted where there was like a 40+HP gain by running thinner oil, i think it was straight 0w

 

yes runs great, i use REdline 5w30. Occasionally I use Redline 10w30 like I put in last week.

 

I try for the seasonal oil change 5w30 summer and 0w20 winter. With low miles it hasnt always worked out. Running the 5w30 in winter was fine. Granted this is Texas and not bitter cold like like many states have. I still try to change it out for the 0w cold flow benefits even if low miles on the 5w30.