I have a 2010 5.4 4x4 Screw with the 6-spd tranny and 3.55 gears, and I was hoping to get some advice regarding changing drivetrain fluids.

I bought the truck new in January 2011, and it's a few hundred miles south of 20k. At least two thirds of those miles have been used towing a 5500lb travel trailer, the reason I bought the truck. We're about ready to begin its third season of camping. I've changed the oil every 5000-7500 miles, but I've never changed tranny, diff, or transfer case fluids. The manual doesn't recommend that any of them be changed before 30k miles under normal use, but my use isn't normal.

Would you recommend changing any or all of these fluids at this time? If so, which ones? And should I use anything other than Ford's OEM fluid recommendations? I appreciate the advice.

 

I have the same engine/gears as you and I too have not changed fluids yet, I have 55k on mine so far and just checked the trans fluid level during the oil change for 55k, the service manual states its a 150k synthetic fluid (Mercon LV) for normal use or every 36k for severe service. The diffs also use synthetic base oil so its a 150k deal, basically its up to you what you want do do.

If I was towing that weight, I would check fluid levels every other oil change (I do 5k interval w/syn blend) and I would do a fluid change at 40-50k depending on how your fluid looks (LV should be red, not muddy brown)
Personally I would only buy the motocraft mercon LV fluid and filter for trans service to be safe, diff fluid is 75-140 synth so whatever brand you prefer for that, and don't forget transfer case if your going all out lol

 

Thanks. I appreciate your feedback.