Manual transmission & Rear End Fluid

[BadQ45t]

I'm going to be doing a transmission and rear end fluid change next week. I know everyone talks about synthetic for autos but what about the manuals? Also, I know the rear end has fluid, not exactly sure what upgrades synthetic are available.

What is the best to put in?

[NISTECH]

they offer synthetic gear oil too. the trans and the rear end use the same weight gear oil. if you have a posi rear end you will want to put in some LSD additive as well.

[BadQ45t]

Thanks, I think I have posi, the 84's came with it as I remember. Does the transmission and rear end take the same fluid? Any particular brands?

[NISTECH]

i swear by valvoline lubricants. yes they take the same fluid

[BadQ45t]

Cool, do they have an synthetic one available??? I haven't seen one, but my mechanic uses Valvoline, you think it is worthwhile to get synthetic or should I just have him put in the regular stuff?

Also, anybody have any ideas for additives to make the box a little more slippery?

[NISTECH]

I believe they do offer a synthetic gear lubricant. If you do use it that should be enough any additional additive is really not nessesary for the slippery condition you wish to aquire. How ever you should add an LSD additive to your rear end if your Z is truly posi.

[BadQ45t]

Thanks, it was my understanding that it is posi but for sure it is not LSD, lots of people replace their rears with the 87-89' rears that had LSD's.

[NISTECH]

limited slip differential(LSD) and posi are the same thing.