Buckshot 1 15 #1 Posted June 12, 2012 :) I now have the 8 speed installed. Now the gear oil, Tranny manual states, S.A.E. 140 API GL-5 gear oil. Around here it is next to impossible to find straight 140. Can I use a multi viscosity gear oil? Thank you for your time. :USA: Share this post Link to post Share on other sites
SousaKerry 502 #2 Posted June 12, 2012 I use full synthetic 80/90W seems to work just fine for me. The only problem I can foresee is if you do not have good axle seals it may leak out faster Share this post Link to post Share on other sites
Buckshot 1 15 #3 Posted June 13, 2012 :) Sousakerry 2, Thank you for your reply. that is what I used in the 4 speed So I will give it a try. :flags-waveusa: Share this post Link to post Share on other sites
Buckshot 1 15 #4 Posted June 18, 2012 Well I ended up buying 85-140 gear oil. While flushing out the tranny, I noticed I have a axle seal leak. Time to replace both axle seals, am I correct in assuming (I know) that the 4 speed and 8 speed use the same seals? 1" axles. Before refilling the trans. with this high dollar gear oil, can some one advise me on the amount of oil that goes in 8 speed. Thank you for your time. Don B. Share this post Link to post Share on other sites
rmaynard 15,608 #5 Posted June 18, 2012 Anything in the range of 80/90, straight 90, or 85/140 will be okay. If you have a Walmart close by, they have all of them. I use their store brand 85/140 in mine. It costs about $18.00/gallon. You don't need to be too critical about gear oil weight as long as it is somewhere in the area. Just think about how many guys are running around with their trannys half full of water and don't know it, and they seem to work just fine. What 8 speed do you have? Most 8 speeds have a 1-1/8" axle, and therefore have a different seal. The 8 speed holds 2 quarts of fluid. Share this post Link to post Share on other sites
