Paul Dietrich 19 #1 Posted September 16, 2021 What weight oil is recommended for the rear differential of a standard 8 speed transmission. Doing a differential oil change on a 1975 C 16........Thanks in advance.... Share this post Link to post Share on other sites
ebinmaine 67,596 #2 Posted September 16, 2021 These 8-speed rear axle/ transmissions are extremely tough and not overly fussy. I use the least expensive 80w 90 I can get my hands on. Straight 90. 85w140. Anything up in that range would work just fine. Nothing fancy necessary. 3 Share this post Link to post Share on other sites
rmaynard 15,512 #3 Posted September 16, 2021 GL-5 should be in the description no matter the weight. That is an additive that is needed in these types of transmissions. 5 Share this post Link to post Share on other sites
RandyLittrell 3,884 #4 Posted September 16, 2021 1 minute ago, rmaynard said: GL-5 should be in the description no matter the weight. That is an additive that is needed in these types of transmissions. Thanks, I need to remember that info!! Randy 1 Share this post Link to post Share on other sites
clueless 3,002 #5 Posted September 16, 2021 make sure you jack the front of the tractor up at least 18 inches to drain all the old stuff out. Share this post Link to post Share on other sites
Lee1977 6,666 #6 Posted September 16, 2021 GL5 gear oil is for High Temperature and Shock Loading Operation. Unless your pulling stumps you probley don't need it but It will work fine in the late model Wheel Horse transmissions. It's not for use in anything transmission with brass as it is deteriorates brass. I believe the early three piece transmissions use brass bushings. 2 Share this post Link to post Share on other sites
rmaynard 15,512 #7 Posted September 16, 2021 Straight from the Toro/Wheel Horse Lubrication document, with 1975 C-160 highlighted: Since these transmissions have lasted all this time, I will follow what the Ponds decided was best. 4 Share this post Link to post Share on other sites
pfrederi 17,741 #8 Posted September 16, 2021 The cheap GL-5 I get from Wally World says "Protects against rust, foam, high temperature and corrosion of copper or bronze bushings." On the other hand my L-107 which is used year round several times a week in the summer 1-2 times in winter, has been running SAE40 motor oil for 54 years now. Changed every few years. No issues still runs great. Bottom line don't obsess over oil just keep the water out... 5 1 Share this post Link to post Share on other sites
Maxwell-8 4,277 #9 Posted September 16, 2021 3 hours ago, Lee1977 said: GL5 gear oil is for High Temperature and Shock Loading Operation. Unless your pulling stumps you probley don't need it but It will work fine in the late model Wheel Horse transmissions. It's not for use in anything transmission with brass as it is deteriorates brass. I believe the early three piece transmissions use brass bushings. And the reverse gear bushing on later trannys too 1 Share this post Link to post Share on other sites
RandyLittrell 3,884 #10 Posted September 16, 2021 3 hours ago, pfrederi said: Bottom line don't obsess over oil just keep the water out... Yup!!! Exactly! Randy 1 Share this post Link to post Share on other sites
Paul Dietrich 19 #11 Posted September 16, 2021 Great, Thanks again for the info....... Share this post Link to post Share on other sites
Ifixoldjunk 778 #12 Posted September 19, 2021 80w90 is fine for something like a wheel horse. They’re rugged transmissions. Bolens tractors on the other hand, they need fancy gl-4 speck brass safe gearbox oil. I was tearing my hair out looking for some. 1 Share this post Link to post Share on other sites
shallowwatersailor 3,213 #13 Posted September 19, 2021 2 hours ago, Ifixoldjunk said: 80w90 is fine for something like a wheel horse. They’re rugged transmissions. Bolens tractors on the other hand, they need fancy gl-4 speck brass safe gearbox oil. I was tearing my hair out looking for some. Check NAPA. I use to buy GL-4 for my Simplicity Walk Behinds there. 1 Share this post Link to post Share on other sites