I am covered on engine oil but what is the preference on tranny and rearend?

 

After many recommendations on this board, I will be using Red Line MT-90 in the transmission, and Red Line 75W90 in the diff. Both are synthetic. Many people also swear by Royal Purple.

 

While the questions are being asked, I have one:

I have searched for information about what to use as LSD oil but have had no real luck in getting an answer. My friend Eric has an '84GSL, and just wants to get basic gear oil at the store. We asked about "LSD Additive" at about 4 stores and they all just stared at us like cows on the traintracks stare at oncoming trains.

Can you use just synth gear oil without LSD additive? And what weight of oil?

I'd assume that if the stores had never heard of it, than you must be able to because lots of people have LSD in the rear, and they musn't be using it...

Jon

 

Dude! The forum just told me that "This post is a duplicate post of one you have made within the last five minutes, you will be redirected to that post"!

Awesome.. we have auto-doublepost-protection now!

Jon

 

Best source for LSD additive I have found, is the local Ford dealer.
As for synthetic gear oil in an LSD, I have heard yes and no from various sources. Hard to know who to believe.
I just use regular 90W gear lube right now in both the trans and rear diff, but I may switch to synthetic later. (no LSD)
I use synthetic oil in my Nissan truck engine, but I chose Valvoline's "MaxLife" 20-50 for the 7.