I've got a 2005 5.7 that is developing a coolant leak. I can't find any water yet, but I can smell it when the motor is warmed up. all hoses and gaskets appear tight, intact, and non leaking. I'm not losing any water, but Something is about to give.

Since the truck is 9 years old and has 120k miles on it, I'm thinking I may need to do some preventative replacement of hoses and such anyway.

Since I'll climbing around under the hood already, I figure an electric fan may be a good idea. A couple of questions, though.

What brand have people had the most luck with? I spend most of my miles stuck in 115 degree weather, crawling at 10mph in traffic for 60 miles a day, and I want something that will survive.

Have those who've made the switch noticed any gas mileage or power improvements?

 

DS:
At this juncture, if your D is on the OEM coolant and hoses it is time for a good PM.
I recommend new coolant, hoses, and a new T stat as well as replacing the stamped metal snout that holds the T stat in.
Mine had rust holes in it which was allowing coolant to seep out and leak down onto the PS pump.

Don't forget a good flush of the system before putting the new coolant in.
While you are at it, replace the fan clutch with an OEM unit and you will be good to go.
I have done this, and the temp gauge stays pretty much around a needles width below the middle mark. On really hot days, it might get to the middle or a width above.

Don