41WindsorHighlander Posted February 25, 2023 Share Posted February 25, 2023 Hi , I want to drain the fluid drive transmission fluid in my 1941 Chrysler Highlander Club Coupe-what type of trans fluid should I fill it with?? Thanks, Rob Link to comment Share on other sites More sharing options...
Rusty_OToole Posted February 26, 2023 Share Posted February 26, 2023 Hydraulic fluid for tractors, TDH type, ISO22 or ISO32 grade. You can get it at auto supply stores, farm supply and Walmart. TDH stands for transmission differential hydraulic fluid. Good for both transmission and fluid drive unit (they are filled separately). Link to comment Share on other sites More sharing options...
Joe Cocuzza Posted February 26, 2023 Share Posted February 26, 2023 45 minutes ago, Rusty_OToole said: Hydraulic fluid for tractors, TDH type, ISO22 or ISO32 grade. You can get it at auto supply stores, farm supply and Walmart. TDH stands for transmission differential hydraulic fluid. Good for both transmission and fluid drive unit (they are filled separately). What Rusty said. And I am sure if my advice below is wrong he will correct me. (hopefully kindly) But I have to ask this question. Are you having problems with the operation of the Fluid Drive or do you just feel the need to change the oil??? I am of the belief that if all is operating correctly then don't mess with it (unless the fluid level is low and that can cause issues). I have the original fluid in my 48 Chrysler and have NO problems with the transmission. Link to comment Share on other sites More sharing options...
Bryan G Posted February 26, 2023 Share Posted February 26, 2023 The ultimate modern replacement appears to be Mobil DTE Light ISO 32 Circulating Oil, per research conducted by one owner. Special order for most folks, and rather expensive. Any of the stuff Rusty suggested will work, though. On some levels, most anything liquid might work, but remember there is a bearing in there that needs lubrication, and that fluid gets tossed around quite a bit and is subject to foaming/expansion. Better products have additives to prevent issues. Link to comment Share on other sites More sharing options...
marcapra Posted February 26, 2023 Share Posted February 26, 2023 (edited) I think if you look at the OP question, he is asking what to put in his transmission, not his FD. But after reading his question again, he may mean the FD. Most people are not sure how to ask the precise question. The shop manual answer to that is 10 W non detergent oil for the transmission. 10W oil is not found at your local auto store, but can be ordered from Amazon. What Rusty said it probably good or better also, but I have no personal knowlege of it. For transmission gearbox: https://www.ebay.com/itm/163852887598?var=463422828185 For Fluid Drive coupling: https://www.amazon.com/Mobil-DTE-Light-ISO-gal/dp/B07CSLKT1J/ref=sr_1_4?crid=3CE4TU8OAK6BL&keywords=mobil+one+light+circulating+oil+iso+32&qid=1677391426&sprefix=mobil+one+light+circulating+oil+iso+32%2Caps%2C115&sr=8-4&ufe=app_do%3Aamzn1.fos.304cacc1-b508-45fb-a37f-a2c47c48c32f Edited February 26, 2023 by marcapra (see edit history) Link to comment Share on other sites More sharing options...
Rusty_OToole Posted February 26, 2023 Share Posted February 26, 2023 Transmission and fluid drive are filled separately but both use the same oil. Once upon a time they made a special fluid drive oil but that has been unavailable for many years. 10W motor oil is recommended instead. But the TDH oil has additives that are beneficial in this case. Manufacturer recommends changing transmission oil every 10,000 miles. No need to change the fluid drive oil, it is a sealed unit and never gets dirty. They suggest checking level every 10,000 miles and topping up as necessary. But, they probably did not envision they would still be in service after 70 or 80 years. 1 Link to comment Share on other sites More sharing options...
41WindsorHighlander Posted February 27, 2023 Author Share Posted February 27, 2023 On 2/25/2023 at 9:08 PM, Rusty_OToole said: Hydraulic fluid for tractors, TDH type, ISO22 or ISO32 grade. You can get it at auto supply stores, farm supply and Walmart. TDH stands for transmission differential hydraulic fluid. Good for both transmission and fluid drive unit (they are filled separately). Hi Rusty, The car has not been driven in 20 years- I want to make certain the fluids are there and are good. Where is the transmission check level(or add fluid) plug?? Where is the Fluid Drive check level (or add fluid) plug? I have an original shop manual and it is difficult to see this in the car- The shop manual shows pictures of the trans and drive out of the car. Please advise. Thanks, Rob Link to comment Share on other sites More sharing options...
Jeff Perkins / Mn Posted February 27, 2023 Share Posted February 27, 2023 On my 1948 I removed the front carpet and pad, exposing the center hump. One can remove a panel there and access both trans fill plug and the cover to access the fluid clutch port. You may have to turn the motor a little to bring the access plug in sight. I used ISO 32 fluid as recommended by @Rusty_OToole. Link to comment Share on other sites More sharing options...
Marty Roth Posted February 27, 2023 Share Posted February 27, 2023 Back in the late 1950s and early 1960s, I worked part time for an auto parts wholesaler. The recommended fluid for Chrysler corp Fluid Drive was straight 30 weight oil, but more modern fluids, as suggested by @Rusty_OToole should be an improved alternative, at least in my opinion. Link to comment Share on other sites More sharing options...
Rusty_OToole Posted February 28, 2023 Share Posted February 28, 2023 (edited) For the Fluid Drive there is an access plate in the transmission tunnel, below the dash board on the right side. Roll back the carpet and take off the plate. Underneath you should see the bellhousing with a round knockout plug. Pry out the plug and "bump" the starter until the fill plug comes into view. Unscrew the plug and top up the fluid using a funnel. Pro tip: Before taking out the plug stuff a rag around the hole. This will prevent dropping the plug down inside the bellhousing. I would hate to tell you how I found this out lol. The angle of the fill hole means you can't fill the Fluid Drive fully to the top. There is a reason for this, they want to leave an air space so the fluid can expand when it gets hot. Otherwise it could build up so much pressure it could blow the seal. The transmission can be accessed from under the vehicle. There are 3 pipe plugs that screw into the trans. A drain plug at the bottom, a fill plug half way up the right side, and another near the top. Not sure what that one is for. Take out the fill plug and stick your finger in the hole. If you touch oil it is fine, if not, put in oil until it drips out. You may need a squeeze bottle for this or go thru the access hole in the floor. If you want to change the oil drain the old oil by taking out the drain plug. A little teflon tape will help the plugs seal. The thinner the oil the more efficient the Fluid Drive works. This is why they recommend 10W oil or thin oil. Edited February 28, 2023 by Rusty_OToole (see edit history) Link to comment Share on other sites More sharing options...
Rusty_OToole Posted February 28, 2023 Share Posted February 28, 2023 Here is a good trick for removing pipe plugs with a square head. Use a socket extension of the appropriate size, turned backwards. It will fit perfect over the square plug. Then use a 12 point socket on the end of the extension. 2 Link to comment Share on other sites More sharing options...
8E45E Posted February 28, 2023 Share Posted February 28, 2023 On 2/25/2023 at 8:57 PM, Bryan G said: The ultimate modern replacement appears to be Mobil DTE Light ISO 32 Circulating Oil, per research conducted by one owner. Special order for most folks, and rather expensive. Any of the stuff Rusty suggested will work, though. On some levels, most anything liquid might work, but remember there is a bearing in there that needs lubrication, and that fluid gets tossed around quite a bit and is subject to foaming/expansion. Better products have additives to prevent issues. The synthetic stuff is probably the best bet for a car that won't be driven daily. Less chance for it to absorb moisture from temperature swings. Craig Link to comment Share on other sites More sharing options...
Marty Roth Posted February 28, 2023 Share Posted February 28, 2023 19 minutes ago, Rusty_OToole said: The transmission can be accessed from under the vehicle. There are 3 pipe plugs that screw into the trans. A drain plug at the bottom, a fill plug half way up the right side, and another near the top. Not sure what that one is for. Take out the fill plug and stick your finger in the hole. If you touch oil it is fine, if not, put in oil until it drips out. You may need a squeeze bottle for this or go thru the access hole in the floor. I think I know what the fill plug near the top is for - at least similar to adding oil to a 1914 Buick B-37 Engine. If you remove both the fill plugs, and then add oil via the top hole until the oil just begins to seep out of the one half way up on the right side, you will have topped off to the desired, and maximum safe level without overfilling - and it is easier to add oil through the access from the top, rather than having to use a syringe. Link to comment Share on other sites More sharing options...
c49er Posted February 28, 2023 Share Posted February 28, 2023 (edited) The 1946-48 Chrysler M-5 transmission square fill plug is marked yellow as shown in the picture half way up.. Use that plug... no others as they access pressure control springs/valves or the piston shift rail screw. Edited February 28, 2023 by c49er (see edit history) 1 Link to comment Share on other sites More sharing options...
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