Questions about a 66 custom camper.

[1966chev]

Hello, I recently started working on my grandpas 66 Chevy. It has a 327, manual 4 speed. I have a few questions and wanted to come to the experts.

First, what oil does the transmission and rear end use, or what should I use?

How about oil for the engine? Would I need any additives?

[65truckowner]

if you mean what gear oil does the transmission and rear end use I would go with a good quality 80-90w gear oil. . 10w40 on the engine. I would just change the oil and filter.

[1966chev]

Okay thanks. Yes I did mean oil. Just putting this out there but one of my buddies said this:

Do not use 80 90 oil from the parts store it will eat the brass shift rings. Use 50 wt non d with a additive for the shift rings.

What do you think of this?

[66Submarine]

It is supposedly slightly corrosive to the brass parts. I think GL-4 is considered ok by most, GL-5 being the most harsh to the brass and what most people recommend not using. You can also get the old GL-1 straight 90 weight at NAPA, which I used in my SM420 4 speed (the 2nd gear synchro is NLA for them, so I wanted to avoid any potential undue wear). I'd swing by NAPA and get a gallon of GL-1 90w for the trans and use whatever 80w-90 for the rear end. Cool truck