I've heard that. I only put 4 in when I did mine because of the leak. But it hasn't leaked since, but I also haven't been parking downhill at all. Gonna put an extra quart in and see what it does. I would like to add coolers to mine. Pulled a 39ft (bumper to tongue) toy hauler 800 miles last week. Almost 9,000 lbs. my truck spends half of it's life towing, so I need to take care of the drive line. I do towaway for a company up north delivering travel trailers to dealerships. So when you put the coolers on the pto covers, did you just put fluid in until it reached the top pto bolt? I'm new to these. This is my first diesel. But I'm a stickler for maintenance and caring for my vehicles as well. So I wanna do whatever it takes to keep it going well past the quarter million mark. It's been a good truck so far, but I've put less than 10k on it

 

I believe when I put my coolers on, on level ground I filled it up to the fill hole on the drivers side of the trans. At that point, I couldn't get all 7 quarts of fluid in (only maybe 5.5- 6?). I had the luxury of being able to drive my driver side onto an embankment to get the driver side higher so I could then continue to get 7 quarts in through the fill hole. Others have taken the shift tower off from above and added more fluid, but I think my particular method was faster and less invasive on the interior. I highly recommend the fast coolers I have, especially if you're towing a lot. They're pricey, but repairs for your trans if you get it hot are even more pricey.

 

I'll keep that in mind. So I guess you can't use the top pto bolt then with the coolers. I'll look them up. I only towed 230ish miles today with a small (26ft) trailer. Tomorrow is the same with a 24ft so that's not bad. What bothers me the most is when I pull a 39 900+ miles like I did last week. I'll look into throwing those coolers on. Won't be long until I change trans fluid again anyway. 3,000 miles a week adds up quickly