Changed Transfer Case ATF fluid

[rumple]

I have a 2002 Ford Explorer with 60,900 miles that I purchased new back in the day. I recently got auto maintenance do it yourself bug and it's fun to be working on cars again.

Ford spec'd Mercon in the transfer case rather than the Mercon V used in the automatic transmission. Since Mercon has now gone to the happy lubricating fluid hunting grounds I used Mobil 1 Synthetic ATF that fulfills the Mercon V standard, and several others (see here).

The old fluid was a medium brown rather than red or pinkish of new ATF. It didn't smell burnt, but certainly didn't look good. I have never towed with the Explorer and Ford has no interval on changing it. Looks like to me 60,000 miles was a bit long for it.

Next up are the limited slip D4 rear differential spec'd for 75W140 synthetic , the front differential spec'd for 80W90 and the automatic transmission spec'd for Mercon V.

I thought I would try Amsoil 75W110 in the rear as I use the explorer in light duty, Amsoil 75W90 in the front and use Mobil 1 synthetic ATF in the auto transmission. I suppose I could be talked in to using Amsoil ATF or Redline D4 for the transmission instead of Mobil 1.

Rumple

 

[Pablo]

If the rear calls for 140, use 140. If the front calls for 90, use 110.

I recommend Amsoil ATD for the transfer case.

 

[rumple]

Interesting. Why go one grade heavier in the front and stick to spec in the back? I thought I would see if I could squeeze out a wee bit of extra MPG by going lighter. I assume you recommend against it due to extra wear? I'm new at this game so any advice/explaination greatly appreciated.

What do you recommend for the 5R55S no dipstick automatic transmission? I was thinking about just doing a pan drop change rather than going to a shop and have it flushed.

Thanks,

Rumple

Originally Posted By: Pablo
If the rear calls for 140, use 140. If the front calls for 90, use 110.

I recommend Amsoil ATD for the transfer case.

 

[MolaKule]

I think he is recommending the 75W110 in the front differential instead of 75W90, which is slightly thicker and gives better wear control, a widely made recommendation according to the SAE's new viscosity charts.

 

[Pablo]

Exactly. Old 90 is now two ranges, split in two new 90 and 110.

http://www.widman.biz/Seleccion/Viscosidad/SAE_J306/SAE_J306_English/sae_j306_english.html

http://www.lubrizol.com/products/automotive-gear-oil/J306.asp

 

[astraelraen]

Wow thats good information guys. It looks like a lot of 75w90's are actually 110's now.

 

[rumple]

Update:

I got the itch to change out the differential oils, went to the local NAPA and used Valvoline SynPower full synthetic 75W-90 in the front and Lucas 75W-140 in the rear of the 2002 Explorer. The Lucas oil claims to have the limited slip friction modifier already in the oil and my rear differential is indeed not making any chattering when turning sharp corners.

The old rear diff oil was black when it came after the 61,000 miles. According to the manual the old oil was synthetic. The front oil came out a dark grey which was a surprising colour. Again, according to the manual the old oil was not synthetic but conventional based 80W-90.

Rumple