So I have a couple questions about a couple fluid change intervals.

I have an owners manual somewhere, but can't right it right now.

I have a 2003, 5.4, 4x4 with a 3.55 and factory limited slip. I just hit 90,000 miles this week.

I did the first transmission fluid change around 50,000 miles and again just recently around 85,000. So thats good for a bit.

My rear differential fluid was changed around 45,000 miles, when the dealership changed out the clutch pack in the limited slip rear, as part of the sale. No issues since.

Now I'm wondering about the transfer case- I assume its the original oil since I bought the truck with relatively low miles (~45,000), as well as the front differential fluid. At 90,000 miles, I should definitely have both of these changed, correct?

Thanks for reading

 

Yes, I would change them. Just a note on the transfer case, do not use Mercon V. It will trash your t-case.

Watch this video for a better explanation.


I used this in my truck, and it's been great!

https://www.castrol.com/en_cc/ccsa/p...-dex-merc.html

 

Thanks for the info.

I'm assuming that he means to use only this stuff:

 

Yes, that is correct. The stuff I posted will work as well, and it is only Mercon, not Mercon V.

 

So they still make a Mercon formulation? Thought they did away with it completely. It was the worst for the transmissions. Does it say Mercon on the back of the label or was it in the video ?

 

This just says Mercon. I think it might be Mercon III though? I was thinking the Dexron III and Mercon III went together (were compatible), but I don't know the older stuff as well.

https://www.castrol.com/en_cc/ccsa/p...-dex-merc.html

 

Huh. I can't recall what I used last time. From what I hear, it must of been the right stuff lol.