75W140 - Lucas out Amsoil in

[rumple]

I recently replaced the rear differential oil in my 61,000 mile 2002 V6 Ford Explorer. Ford calls for synthetic 75W140 and I used Lucas synthetic 75W140 gear oil. The Lucas oil stated that it already had a limited slip friction modifier in it.

However, I have been noticing some chattering from my limited slip rear differential. I also wasn't real comfortable with Lucas quality/reputation. Today I drained the Lucas and put in Amsoil 75W140 sever gear oil and added the required 4oz of limited slip friction modifier. Chattering gone and I feel better.

Rumple

 

[buster]

Good move. Amsoil is a much better choice.

 

[dargo]

what I do not get is for years Amsoil said they did not need the chatter fluid. I used there blue gear fluid (2000) for years and worked well. I still would like to know why they went backwards.

 

[Johnny]

The Severe Gear 75W-140 has LS additive already in it. This is from their spec sheet:

AMSOIL SEVERE GEAR® is compatible with most limited slip differentials. If limited slip differential chatter occurs, add AMSOIL Slip-Lock™ friction modifier additive.

I put some in my Jeep and there was not chatter at all. Product works great straight out of the bottle.

 

[rumple]

After the chatter I had with the Lucas which was supposed to have the friction modifier all ready in*, and not wanted to open up that differential again I put the 4oz of friction modifier in up front with the Amsoil.

Rumple

*perhaps it did but my diff still chattered - I wonder if the D4 diff on the 2002 Explorer is more prone to this than some other designs?

 

[c3po]

I have an 04 Marauder and used the Amsoil 75W-140 but I added the Ford friction modifier and no problems, you need the Ford friction modifier.