Hedley8888 11 #1 Posted November 1, 2020 Hello I have been gifted a '75 C-120 8 speed. its not been used for a time, so thought it would be good to change oils etc The owner manual says the trans oil is SAE 140 GL-5, so I got a bottle as per picture - is this the right one? Its as thick as hell. like treacle. even the guys in the tractor shop asked what I was running. Is this still the right grade for an old boy like my C-120? would you stick to this or use a slightly lighter grade? Any suggestions welcome 3 Share this post Link to post Share on other sites
953 nut 55,771 #2 Posted November 1, 2020 23 minutes ago, Hedley8888 said: I have been gifted a '75 C-120 8 speed. What a wonderful gift, was it a family heirloom? The most common gear oil here in the states is SAE 80-90. Be sure to jack up the front of your while draining the transmission for best draining. 3 Share this post Link to post Share on other sites
SylvanLakeWH 25,927 #3 Posted November 1, 2020 (But what you bought will certainly work... ) Share this post Link to post Share on other sites
Pullstart 63,096 #4 Posted November 1, 2020 Great tractor you’ve got! Yes, there’s a hump in the middle of the transmission. It’s common for us folks to drain with the front end lifted high as safely possible, then flush the transmission with diesel fuel or kerosene, as many times as needed until it runs clear, then refill. I like to jack up the left side of the tractor for filling through the fill hole near the left rear corner of the case, or you could pull the fender pan and shifter and fill through the shifter hole. 1.5-2 qts is good. At level, 1.5 qts will fill the case. 2 CT’s is what some limited slip gear cases run, so I figure it’s safe to add a little extra. 2 Share this post Link to post Share on other sites
Hedley8888 11 #5 Posted November 1, 2020 Thanks 953Nut & SylvanLakeWH it was in the garage when I bought my house. It has been with the property since 1975. I am its new custodian. I bloody love this Wheelhorse. its so handsome 5 2 1 Share this post Link to post Share on other sites
Hedley8888 11 #6 Posted November 1, 2020 Pullstart - so there is another fill point? I can only see to add oil via the dip stick hole. will be very slow to fill through this, especially as the oil is so thick do you think 140 is the best grade ? Share this post Link to post Share on other sites
oliver2-44 9,856 #7 Posted November 1, 2020 That a great looking C-120. One of he best GT's wheelhorse made. The 12hp is easy on fuel, but enough power to run almost any attachment. 3 Share this post Link to post Share on other sites
tom2p 2,394 #8 Posted November 1, 2020 2 hours ago, Hedley8888 said: Thanks 953Nut & SylvanLakeWH it was in the garage when I bought my house. It has been with the property since 1975. I am its new custodian. I bloody love this Wheelhorse. its so handsome great looking C-120 - and great house warming gift ! 2 1 Share this post Link to post Share on other sites
peter lena 8,721 #9 Posted November 1, 2020 HEDLEY, having recovered a few tractors , I found that transmission lubrication issues ,go hand and hand with neglect . usually the drain and refill , is not , a 1 and done service. I get the best results with hours of use and road time , visualize that new oil cleaning / lubricating and flushing out the moisture and crud that was inside. Use every gear and hi/lo range to operate and lubricate each function. found the second oil change , is the best gain , as it stays looking fresh with no issues , shifting is easy and smooth . also detail lube every spot on the clutch linkage, to insure there are no hang ups. change the shift boot . found most w/h linkage to be neglected ,with solid rust and often binding , regularly detail lube everything on your horse , and feel how easy it goes about its work. good luck with your recovery , keep us informed , pete 1 1 Share this post Link to post Share on other sites
8ntruck 7,083 #10 Posted November 1, 2020 Nice tractor. Don't force the high/low range lever, as the shifter fork can be damaged. It is not uncommon on mine to have to let the clutch out a bit to get the gear teeth to line up for easy engagement. When all is lined up, pressure from one or two fingers will make the shift. 3 Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,096 #11 Posted November 3, 2020 Wheel Horse published a lubrication chart in the later years and state the recommendations now may be different than what is in older manuals. The bottle you have is for a later multi-weight oil 85W-140. Acts like 85 weight in cold winter conditions and 140 weight in hot conditions. The 2 pages for the 1975 C-Series are here. Click on the picture. First one lists the models with yours showing T3 for the transmission. Second picture describes T3. Garry Share this post Link to post Share on other sites
The Tuul Crib 7,337 #12 Posted November 4, 2020 On 11/1/2020 at 6:29 AM, 953 nut said: What a wonderful gift, was it a family heirloom? The most common gear oil here in the states is SAE 80-90. Be sure to jack up the front of your while draining the transmission for best draining. 1 Share this post Link to post Share on other sites
The Tuul Crib 7,337 #13 Posted November 4, 2020 Nice rig and truly a survivor! Spit shine and a tuneup you'll be good to go. T😎 Share this post Link to post Share on other sites
sqrlgtr 552 #14 Posted November 4, 2020 NICE!!! If it where me I would just use the oil you got for a little while then change it again later with 80-90(little easier shifting lol).I run it year round myself and always thought the 140 was to thick especially in the winter.Just myworth.... Share this post Link to post Share on other sites
WHX?? 49,158 #15 Posted November 5, 2020 Sounds like the fellas got you covered so I'll just Those early 70s c series are always favs with me Share this post Link to post Share on other sites
12Horse Paladin 1,038 #16 Posted November 5, 2020 On 11/1/2020 at 8:35 AM, Hedley8888 said: Thanks 953Nut & SylvanLakeWH it was in the garage when I bought my house. It has been with the property since 1975. I am its new custodian. I bloody love this Wheelhorse. its so handsome Finest WH made, some might say... (Or just me😉😊 ) Welcome! Like those Ags on the back!👍🏼 1 Share this post Link to post Share on other sites
AHS 1,443 #17 Posted November 12, 2020 On 11/1/2020 at 7:02 AM, Hedley8888 said: Hello I have been gifted a '75 C-120 8 speed. its not been used for a time, so thought it would be good to change oils etc The owner manual says the trans oil is SAE 140 GL-5, so I got a bottle as per picture - is this the right one? Its as thick as hell. like treacle. even the guys in the tractor shop asked what I was running. Is this still the right grade for an old boy like my C-120? would you stick to this or use a slightly lighter grade? Any suggestions welcome Great tractor!!! 80w-90 would be fine. On my 3 8-speeds it worked fine. It only goes 7 or 8 mph! Did I mention Great tractor!!!! 😀💪 Share this post Link to post Share on other sites
Lee1977 6,777 #18 Posted November 15, 2020 On 11/1/2020 at 2:50 PM, 8ntruck said: Nice tractor. Don't force the high/low range lever, as the shifter fork can be damaged. It is not uncommon on mine to have to let the clutch out a bit to get the gear teeth to line up for easy engagement. When all is lined up, pressure from one or two fingers will make the shift. Only shift the high low when completely stopped. It's best to give all the other gears a few seconds after pushing in the clutch to let everything stop to keep from grinding the gears. Share this post Link to post Share on other sites
