My fan never even kicks on unless I'm really low on coolant... so all the time. J/k. Kind of.

There was some talk of going to e-fans on some of the powerstroke boards. Basic consensus was it was ok for a truck that never towed, since an e-fan that pulled the same CFM as the stock fan could not be found.

 

electric fans might be in my future but right now with the cooler weather and not needing the A/C yet, i am going to test this for as long as i can until the summer comes around.

want to see if there are any worthwhile gains first. for the few times that i do tow i can quickly throw on my fan and not worry about it.

 

We run 15w-40 and it performs just fine

 

i know it does. i was wondering if lighter weight would perform better in terms of MPGs but still provide the protection of the 40w for a daily driver

 

I don't know how much mpgs you will pick up...I didn't notice any when I ran T5 10w30 in my 7.3 but it was also the winter...

But as far as wear protection it looks like the 30wts do just fine...

03 Cummins, 6,500 miles, Rotella T 10w30 - Bob Is The Oil Guy
Rotella 10w-30 dino CJ-4 6.5k miles; Dmax LBZ - Bob Is The Oil Guy
JD plus 50 10w-30 07 powerstroke - Bob Is The Oil Guy
'07.5 Chevy DMax Rotella 10W-30 CJ-4 5,105 miles - Bob Is The Oil Guy

 

i think i will try some 30w for my up coming oil change

 

I've been using 15-40 for so long & it get real hot where I live, i'm sticking to 15-40

 

Synthetic oils are known to lower friction and therefore they allow up to 2% savings in fuel.
I use 0W 40 during the cold season, because cold start friction consumes a lot of fuel.

Savings from switching an AT tire to a pure onroad tire are significantly higher than switching oil viscosiy.
I'm happy to have an onroad set of tires. Sadly I have to store two sets of tires now.