# Why is it called transmission fluid instead of transmission oil? **URL:** \ **Category:** General Discussion\ **Created:** [April 21, 2020, 12:08am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165 "2020-04-21T00:08:02Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Barkydog](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/barkydog/32/2470_2.png) [@Barkydog](https://community.cartalk.com/u/Barkydog)\ **Post date:** [April 21, 2020, 12:08am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/1 "2020-04-21T00:08:02Z")
Bored I guess! 20 characters! ---
**Author:** ![B.L.E](https://avatars.discourse-cdn.com/v4/letter/b/848f3c/32.png) [@B.L.E](https://community.cartalk.com/u/B.L.E)\ **Post date:** [April 21, 2020, 12:36am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/2 "2020-04-21T00:36:42Z")
Why is it called a transmission instead of a gearbox? ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [April 21, 2020, 12:50am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/3 "2020-04-21T00:50:11Z")
Here’s a guess - because it’s used to transmit power, not just to lubricate? Like brake fluid and power steering fluid? ---
**Author:** ![It\_s-Me](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/it_s-me/32/12660_2.png) [@It\_s-Me](https://community.cartalk.com/u/It_s-Me)\ **Post date:** [April 21, 2020, 1:28am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/4 "2020-04-21T01:28:17Z")
So is it “Jack Fluid” or “Jack Oil” in a hydraulic jack ? ---
**Author:** ![Triedaq](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@Triedaq](https://community.cartalk.com/u/Triedaq)\ **Post date:** [April 21, 2020, 1:31am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/5 "2020-04-21T01:31:06Z")
I think we called the liquid in a manual transmission and differential oil. The oil is there to lubricate. In an automatic transmission it transmits power, so it is called a fluid. Similarly, the oil in an engine us primarily there to lubricate, so it is called engine oil. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [April 21, 2020, 1:33am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/6 "2020-04-21T01:33:01Z")
> [@It\_s\_Me](#): > > So is it “Jack Fluid” or “Jack Oil” in a hydraulic jack ? I’d call that ‘hydraulic fluid’. ---
**Author:** ![It\_s-Me](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/it_s-me/32/12660_2.png) [@It\_s-Me](https://community.cartalk.com/u/It_s-Me)\ **Post date:** [April 21, 2020, 2:25am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/7 "2020-04-21T02:25:30Z")
> [@texases](#): > > I’d call that ‘hydraulic fluid’. I’d call it “Hydraulic Oil”, I wouldn’t want to use air or water which are both considered fluids and would work. ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [April 21, 2020, 5:25am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/8 "2020-04-21T05:25:34Z")
I have seen hydraulic fluid labeled as Jack oil and also as hydrualic fluid for jacks, ---
**Author:** ![tom418](https://avatars.discourse-cdn.com/v4/letter/t/da6949/32.png) [@tom418](https://community.cartalk.com/u/tom418)\ **Post date:** [April 21, 2020, 10:39am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/9 "2020-04-21T10:39:44Z")
I just checked my bottle of floor jack fluid (from Car Quest). It’s labeled as “Hydraulic Jack Oil”. Come to think of it: Why do we call it a hydraulic JACK? Are there any Hydraulic JILLS out there? 😉 This isolation is taking its toll on me. ---
**Author:** ![Honda-Blackbird](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/honda-blackbird/32/3159_2.png) [@Honda-Blackbird](https://community.cartalk.com/u/Honda-Blackbird)\ **Post date:** [April 21, 2020, 11:11am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/10 "2020-04-21T11:11:49Z")
Want to know? My take is because it adds an “Air of Mystery” to it… and thusly… you can charge 4-5x more per gallon. It’s genius i tell ya… Evil genius. All any hydraulic needs to function is a liquid… which as physics dictates…cannot be compressed. You can put tap water into a jack and she will function just fine…till it rusts inside…lol…so an oil of some type is preferable but I digress… ---
**Author:** ![Rod-Knox](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Rod-Knox](https://community.cartalk.com/u/Rod-Knox)\ **Post date:** [April 21, 2020, 11:26am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/11 "2020-04-21T11:26:57Z")
Potato Potah-to Tomato Tomah-to For the totally BORED looking for something controversial to debate look what pops up ---
**Author:** ![Honda-Blackbird](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/honda-blackbird/32/3159_2.png) [@Honda-Blackbird](https://community.cartalk.com/u/Honda-Blackbird)\ **Post date:** [April 21, 2020, 11:36am UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/12 "2020-04-21T11:36:59Z")
LOL… @Rod_Knox we could discuss “Right to Repair” type stuff… I just rewatched an older video that shows how John Deere has tried to completely remove the farmer from repairing their own (very expensive) equipment by making it nearly impossible to pull codes and read diags to help them repair a machine. A machine that will not function when one of its numerous sensors goes out to lunch…it aint right man…it aint right. I started a thread about it long ago… Lots to discuss within the topic. They are struggling to re-do the legislation on this, they claim that if they remove the computer barrier that the issue will carry over to other devices like phones etc… So its getting hung up in red tape. Total BS… ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [April 21, 2020, 12:59pm UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/13 "2020-04-21T12:59:41Z")
They pass 1000’s of new laws. So, pass 1 law to allow repair of tractors only. The combine folks can just deal with it. ---
**Author:** ![Honda-Blackbird](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/honda-blackbird/32/3159_2.png) [@Honda-Blackbird](https://community.cartalk.com/u/Honda-Blackbird)\ **Post date:** [April 21, 2020, 1:34pm UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/14 "2020-04-21T13:34:00Z")
Exactly @Cavell or word it some type of way that concerns motorized farm equipment or something. I think this resistance is a harbinger of things to come… like one day when no farmer rides on his motorized equipment…or really interfaces with it much more than to refuel or resupply the contents that it deals with. The days of the autonomous farm or something…and they wont want you messing with that sort of equipment… It seems to be moving in that direction…so the delays and red tape may just be an indicator of what they know and what we dont type of thing? I dunno… I think I’m making some kind of sense, but I cant usually tell. ---
**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\ **Post date:** [April 21, 2020, 1:36pm UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/15 "2020-04-21T13:36:59Z")
Or why do New Yorkers drink Egg Cream that does not contain eggs? ---
**Author:** ![chunkyazian](https://avatars.discourse-cdn.com/v4/letter/c/7993a0/32.png) [@chunkyazian](https://community.cartalk.com/u/chunkyazian)\ **Post date:** [April 21, 2020, 1:49pm UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/16 "2020-04-21T13:49:48Z")
> [@Honda\_Blackbird](#): > > any hydraulic needs to function is a liquid… which as physics dictates…cannot be compressed. Liquid can be compressed, just not in a scale that you would notice. If liquid cannot be compressed, sonar would not work ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [April 21, 2020, 1:55pm UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/17 "2020-04-21T13:55:41Z")
Yep, everything is compressible, water, oil, rock, everything. Just not a lot. For water the compressibility coefficient is around 3/1,000,000 fractional change in volume per psi change in pressure. So nothing you’d ever notice. ---
**Author:** ![Honda-Blackbird](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/honda-blackbird/32/3159_2.png) [@Honda-Blackbird](https://community.cartalk.com/u/Honda-Blackbird)\ **Post date:** [April 21, 2020, 1:59pm UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/18 "2020-04-21T13:59:20Z")
No S\*&^ ? @chunkyazian and @texases Hey man… I try to learn something everyday… thanks for the info. Thats one hell of a small fraction for sure. I was not aware… I thought liquids were a no go in the compression sense. Cool. ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [April 21, 2020, 2:28pm UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/19 "2020-04-21T14:28:13Z")
> [@Triedaq](#): > > I think we called the liquid in a manual transmission and differential oil. The oil is there to lubricate. In an automatic transmission it transmits power, so it is called a fluid. And yet GM has used Transmission Fluid in their Manual transmissions. I do see your logic though. It makes sense. ---
**Author:** ![Rod-Knox](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Rod-Knox](https://community.cartalk.com/u/Rod-Knox)\ **Post date:** [April 21, 2020, 2:31pm UTC](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165/20 "2020-04-21T14:31:33Z")
with 1/1million compression the permeability and expandability of the vessel holding the liquid could account for the change in volume. But John Deere, like Detroit in recent decades, would enjoy the certainty of profitable service business by way of fire walling all technical diagnostics and repairs to their dealers. My home town, here in a RTW state, has enacted regulations to restrict homeowners from making repairs worth over $100 without a city code permit and technically that would include replacing a toilet or water heater which most able bodied people are easily capable of. It would seem that painting my own house is now forbidden in fact. I wonder who lobbied for that. [Next page](https://community.cartalk.com/t/why-is-it-called-transmission-fluid-instead-of-transmission-oil/163165.md?page=2)