Jim McGarvie Posted May 21, 2020 Share Posted May 21, 2020 How do I know how much gear oil to buy to change the oil in our differential? I can't find the capacity anywhere in the RV owner manual or in the Roadmaster lubrication guide which came with the motorhome. According to the equipment list we have a Dana S150S. Stamped on the diff housing is "Spicer 360CF102". The rear axle is rated at 13,500 lb. The only online reference I can find seem to indicate it takes 24 pints of oil??!! Seems like a lot to me. Any suggestions? Thanks! Link to comment Share on other sites More sharing options...
Dr4Film Posted May 21, 2020 Share Posted May 21, 2020 (edited) I don't know exactly but it has to fill up not only the center of the differential but also the gear shafts and wheel bearings going to each wheel. I don't think 12 quarts is unreasonable frankly. Drain it first then go purchase the same amount that you need to replace what was drained out. Edited May 21, 2020 by Dr4Film Link to comment Share on other sites More sharing options...
Hotrod - R.I.P. Posted May 21, 2020 Share Posted May 21, 2020 To do a 20k axle on my Dynasty took 4 gallons. I used Lucas synthetic 75w90 gear oil and I am very happy with it... makes the axle very quiet. Some people want one that meets the spicer sharps specification. The Texaco synthetic that monaco put in it smelled and looked bad. I think it was 2015 that I changed it. Link to comment Share on other sites More sharing options...
Hotrod - R.I.P. Posted May 21, 2020 Share Posted May 21, 2020 I forgot to mention the capacity is in the owners manual of my dynasty. Link to comment Share on other sites More sharing options...
Jim McGarvie Posted May 21, 2020 Author Share Posted May 21, 2020 3 hours ago, Hotrod said: I forgot to mention the capacity is in the owners manual of my dynasty. And rightfully so. Not in mine, surprisingly. 3 hours ago, Dr4Film said: I don't know exactly but it has to fill up not only the center of the differential but also the gear shafts and wheel bearings going to each wheel. I don't think 12 quarts is unreasonable frankly. Drain it first then go purchase the same amount that you need to replace what was drained out. Thanks. I crawled under mine and took another look, and that diff housing is huge! I bought three gallons. Link to comment Share on other sites More sharing options...
dl_racing427 Posted May 22, 2020 Share Posted May 22, 2020 My 1993 Dynasty has a 20,000# Rockwell axle. It took around 4 gallons, and I used the recommended Shell Spirax synthetic. It was priced much better in the 5 gallon pail, and I used a pail pump to transfer it into the axle. Link to comment Share on other sites More sharing options...
Jim McGarvie Posted May 22, 2020 Author Share Posted May 22, 2020 3 hours ago, dl_racing427 said: My 1993 Dynasty has a 20,000# Rockwell axle. It took around 4 gallons, and I used the recommended Shell Spirax synthetic. It was priced much better in the 5 gallon pail, and I used a pail pump to transfer it into the axle. Thanks for the info. I don't think I could lift a 5 gallon pail of oil! Link to comment Share on other sites More sharing options...
dl_racing427 Posted May 22, 2020 Share Posted May 22, 2020 3 hours ago, Jim McGarvie said: Thanks for the info. I don't think I could lift a 5 gallon pail of oil! It's actually more convenient. The pail pump replaces the lid, and has a hose and nozzle to fill the diff. You just work the hand pump, and fill the diff in a few minutes. Using smaller containers is a pain, as you're going to spill some every time you switch containers. BTW, the 5 gallon pail only weighs about 35 pounds, and has a handle, so they're not that hard to carry. Link to comment Share on other sites More sharing options...
Jim McGarvie Posted May 22, 2020 Author Share Posted May 22, 2020 42 minutes ago, dl_racing427 said: It's actually more convenient. The pail pump replaces the lid, and has a hose and nozzle to fill the diff. You just work the hand pump, and fill the diff in a few minutes. Using smaller containers is a pain, as you're going to spill some every time you switch containers. BTW, the 5 gallon pail only weighs about 35 pounds, and has a handle, so they're not that hard to carry. Good to know. Thanks. Link to comment Share on other sites More sharing options...
Ivan K Posted May 22, 2020 Share Posted May 22, 2020 (edited) I use low pressure air to push the oil out of the bucket through a hose. Couple of holes in the screw on cap and it's totally effortless. Buying in bulk might pay for the pump however. 5 gal was just right for the big Rockwell axle and oil bath hubs, delivered to the door by Amazon... Edited May 22, 2020 by Ivan K Clarification Link to comment Share on other sites More sharing options...
larry.jervis@att.net Posted May 23, 2020 Share Posted May 23, 2020 Jim, My 04 Diplomat takes 4 Gallons of 75W90 Syn Gear Oil. As others have mentioned, most cost effective way to purchase the oil is in a 5 Gallon Pail. I use a fluid pump rated for fuel and oil, using 1 quart bottles is a real pain and causes a lot of a mess. Best of luck to you either way you chose. Larry 04 Diplomat 36', 07 Dodge Dakota Link to comment Share on other sites More sharing options...
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