Hey guys, I'm planning on changing my front diff oil tomorrow for the first time in the truck's life, at ~75,000km. I already checked and the fill plug and drain plug are both NOT seized. What's the best brand of 75W-90 to buy? Is the motorcraft stuff decent? Better stuff? My manual says it takes 2.0 Litres of fluid, but should I buy 3 just in case?

I'm also not wanting to buy a suction gun, so maybe using a funnel and hose could work?

 

Well I went ahead and did it today without responses to my original post. I found Mobil 1 full synthetic 75W90 and bought 3 bottles (each 946mL or 1qt.). I also bought a turkey baster thinking that I could get away with that, but alas I had to break down and buy a suction gun. After completing the job with the suction gun I couldn't imagine doing it without one. It was really straightforward, I got the job done in about 20 minutes. The old fluid was disgusting. Milky grey and gross. I didn't even need the 3rd bottle. My manual says it takes 2.0L of fluid, but I guess the residual oil in there contributed to me not needing to open the 3rd bottle (each just shy of a litre). I feel good about having high quality oil in there now. Can anyone tell me if that front diff/drive shaft is spinning all the time the truck's moving or only in 4WD?

 

in your model, I THINK its always moving. I think they switched over in 04, but could be wrong.

Glad ya did the fluid swap ! Sorry I didn't see this earlier !

 

The front driveshaft does not turn all the time on an '03. However, the front driver's side axle shaft does (it's splined into the wheel). The passenger side axle shaft is broken in the middle by the CAD, so the spider gears turn any time the wheel turns, even though the driveshaft, ring, pinion, and carrier remain stationary.

 

and how does that differ from the newer 04+ models ?

(honestly asking, and appreciate your input GI, as always )

 

The 04-ups use a vacuum disconnect at the hubs to disconnect the entire front drivetrain from the wheels. It uses vacuum to release the hubs, and they spring locked with no vacuum applied, so in theory, if they're giving you fits and not engaging on the trail, simply disconnect the vacuum line from the solenoid and cap the solenoid, and the 4wd should lock in. The locking hubs in the IWEs allow the entire front drivetrain to remain stationary in 2wd, as well as reduce the wear and tear on the halfshafts, and probably increase mileage a little bit.

 

Thank you very much !

I owe ya one