Hot Rod Forum banner
1 - 5 of 5 Posts

·
Registered
Joined
·
49 Posts
Discussion Starter · #1 ·
Hey guys, I have a question regarding a Chevy 8.5" 10 bolt. I have an 84 Caprice with a Jasper engines built 350, puts about 300 hp and 325 ft lbs to the wheels as per my last dyno run. I have a set of 3.90 gears, posi, I'm trying to figure out what gear oil to choose from, as well as grade. Any ideas on Synthetic, regular oil? I hear 75W90 is a popular grade, however I heard if the rear is going to be working hard to choose something higher. With this 3.90 gears does this technically mean the rear is being "worked hard"? Car isnt a daily driver however it does see some track time. I was thinking royal purple gear oil, however I read bad things that it can damage certain posi units, and since the previous owner rebuilt the rear and installed the gears, I have no idea what might be installed in this thing. I know the posi seems strong, lighting up the tires both tire marks show even markings. Can anyone shed some light on the subject?

-Chris
 

·
Registered
Joined
·
15 Posts
We have had good luck with Shaffers (cant spell today) 75/90. Has a high moly rating which is suppose to work well with posi. Have had the oil in mine checked by oil anylisis 3 times with very minimal fines found.
 
1 - 5 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top