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I'm pretty sure you're fine as long as you add the friction modifier. I did mine last weekend and used Royal Purple 75w-140 since it already had a limited slip additive.
I changed my read dif on my 01 screw, and found the OEM fluid was very clear and clean at 60k miles. As it was draining, I was wishing I had never drained it!
I changed my read dif on my 01 screw, and found the OEM fluid was very clear and clean at 60k miles. As it was draining, I was wishing I had never drained it!
Also the Motorcraft OEM fluid is a synthetic
I saw about the same thing at almost 129k miles...Still good that we changed it anyway.
The Royal Purple that I replace it with was, well, purple. So it will be more difficult to tell the condition of the oil when I drain that out, but who knows how long it will be before that happens.
Good choice in using Motorcraft fluids. I was shocked when I learned the gear oil was synthetic. I use all motorcraft fluids and filters. The trany oil in my 2001 Screw is synthetic too. Ford does not have its head in the sand where fluids and filters are concerned. I have been using the Motorcraft 5-20 oil since new and now have 85k on my truck. The other day I climbed up on the bumper to shine a flashlight down the oil fill tube. I could see the top of the camshaft and a few other engine parts. All were shinny like stainless steel, and I knew the insides of my engine were nice and clean.
Nothing wrong with the Motorcraft stuff but be ready to pay ALOT of money for it. Mobil1, RP, are great also and will cost you less than the OEM fluid, I personally used the cheapest stuff I could find which was Quacker State syn 75w140 and it has worked great so far. Wouldn't hurt to do your front diff as well if you have a 4x4.
The Royal Purple was actually cheaper than other synthetics at the parts store. That and the fact that it already had the limited slip additive made my mind up for me.
Im getting ready to change the gear oil in my rear differential and I was looking in to Mobil 1 75W140, my question is this....it claims to have the LS additive in it already....does anyone have experience in using Mobil 1 in their rear? I have a feeling if I put it in there Im going to end up needing to add the LS additive.
Hey ned, one thing to check on too, is make sure you have a limited slip rear end. If you have an open rear end, I think the friction modifier isnt needed.
I made that mistake - I thought that, on a 4x4, I would have had a LS rear end for sure (I got this used truck in a round-about way, so I didn't have the chance to check for it when I bought it).
Anyway, at, oh, about 88,000 miles my rear differential fluid was DIRTY. I'm talking black, on its way to being grey.
Like I've stated before, the truck was used as an F-250 for its first life, clutch being changed at 50k miles, but I really wasn't happy. When I got in there I did my best to use a magnet to clean up particles, and to wash away debris with new fluid. Still, as of 105k miles with that new fluid, the magnet on the filler-plug was full of debris again. The fluid, however, looked better this time.
Now the front differential's fluid looked brand new, so I didn't change it.
The tranny fluid, however, looked worse than the rear diff's fluid... ouch.
Im getting ready to change the gear oil in my rear differential and I was looking in to Mobil 1 75W140, my question is this....it claims to have the LS additive in it already....does anyone have experience in using Mobil 1 in their rear? I have a feeling if I put it in there Im going to end up needing to add the LS additive.
I would still go the Ford and order the friction modifier, the stuff the oil companies put in there seems to be not enough and you will still get chattering if your accelerate when turning.