When should I have transmission fluid and differential fluid changed?

Someone isn't going to like this.
Never have I ever changed trans. fluid in any of my vehicles.
Never have I ever had trans. issues.

 

They recommend never changing the transmission fluid for a reason. It doesn't make economic sense. Your transmission will easily make it 300,000 to 400,000 miles on the factory fluid. Chances are very good it will end up in a scrap yard before the transmission ever dies. If you change the fluid every 30,000-50,000 miles, you will spend more to have it serviced than it will cost to have the transmission rebuilt. Drive it. If the transmission dies get it rebuilt or replaced. I've never seen any evidence that indicates changing the fluid prolongs transmission life.

I've been driving for almost 50 years. Never once changed transmission fluid and the only transmission issues I've had were electrical. I had 4 vehicles sitting in the driveway with a combined 638,000 miles on the factory transmission fluid. Someone rear ended my son while he was stopped at a traffic light in the Honda last week and totaled it. I'm glad I never paid to have the transmission serviced on that one. Got over 200,000 out of it. I'm at 239,000 on my Tacoma, 139,000 on the F150 and 60,000 on our Explorer. If the transmission dies on either of those today I'm way ahead financially.

 

https://www.tacomaworld.com/threads/3rd-gen-automatic-transmission-fluid-level-check-diy.547455/

 

I have to admit the logic here; through my own experience, and after 57 years of life.

I asked the OP’s questions. I wheel and tow with my truck. To make things simple, it’s engine oil every 5k and everything else at 50. I do my own work.

Good luck!

 

Thanks. Any idea what each of these should run? My dealer quoted me $1800 for both which I thought was insane. I'm trying to find a reputable local shop.

 

Do what makes you comfortable. I will say with the techs I've worked with from Komori, Mitsubishi and Fuji. Like with vehicles, after the press is bought the money is in the service. They require those expensive services in order to keep your warranty, (I've never had to use).
The printing presses I work on require scheduled maint. with overpriced consumable items that can only be purchased through manufacturer.
After I leave the dealer, I never go back.
Did once on a '01 frame recall. and the '16 tps sensor went shortly after I drove it off the lot.
Maintenance is necessary but not by the intervals suggested by the dealer.
Just an opinion.

 

Thought I was the only one

 

It’s really easy to the diffs and transfer. Transmission process just needs to be gone over in your head a few times so that when you do it it just happens. Limited time for temp and level check.

Just do it yourself and keep a large part of that 1800 bucks in your pocket.

 

Never changed transmission fluid in my life and never had a problem. 219k on a Landcruiser, 165k on an Accord and 188k on an 86 automatic (rare) Toyota pickup.

 

Oil is cheap. You change the oil in your engine. Why wouldn’t you change the oil in your transmission and differentials?

41 years of driving and working on my own stuff never had a transmission fail. Never had an engine fail. Never had a differential fail.

 

I am not suggesting you have to or should change the gear lube or transmission fluid. I am only mentioning when and why I did.

I did gear lube change in front and rear diffs and transfer case at 5000 miles. If i had to do it again I would skip the front and transfer case since the lube look just fine and could easily go the 30K toyota schedule. But i had purchased all the gear lube and it gave me a chance to break loose the stubborn front diff drain plug and replace with a regular hex nut version used on lexus vehicles instead of the trouble prone 10 mm allen key version.But what came out of the rear diff wasn't something i wouldn't like to leave in there for 30K or forever. It was full of shiny metal particles which didn't surprise me since ring and pinion gears do naturally wear in together. The magnetic drain plug was full. I cant see this metallic soup being healthy for either the differential bearings or axle seals.
Now that this initial change was done i can go like 60K based on Amsoil recommendations (i dont currently tow)

Cost to do all was about $80 for Amsoil severe gear 75W90 and $10 for the crush washer/gasket set. But as I mentioned the front diff and transfer case were not really needed so you can cut that cost down to $40 if you just do the rear diff.

I do a 3+ quart drain and fill on transmission every 20 K which cost me like $30 for the WS fluid. I have an ultra gauge to monitor the ATF temp so getting the fluid level correct is quite easy. I combine this activity with greasing all the zerks on the driveshaft since I am down there already. Takes maybe an hour on a weekend so no big deal. Overkill probably but cost is so small its not an issue. To add to the "overkill" i have an inline magnefine filter and additional thermostat controlled secondary transmission cooler that only kicks in when temp exceeds 180F.

So $1800 is insane. You can get everything needed for $100 or less for absolutely everything.

Would you want to leave THIS in there for 30K or forever??

 

Here's the other one... not tacoma specific but some good info...
https://youtu.be/jJr30r6RRgw

 

And with the advent of modern solenoid controlled transmissions this article of additional fluid filtration is a good read.
When you combine a solenoid (electro magnet) with the buildup of ferrous particles (iron) in the fluid you get problems.

https://www.motortrend.com/how-to/129-1002-automatic-transmission-and-power-steering-filters/

 

I just drain and refill both diffs, transfer case, transmission, power steering, and coolant at 50K miles. One thing I should do but haven’t is push out and replace brake fluid. I have 186K miles.

 

Since I am retired and am only putting on maybe 3000 miles a year I base by fluid changes on mileage rather than time or I would be doing oil changes every 1500 miles (6 months)

The exception is brake fluid. That I flush at home every two years regardless of mileage. Its a hygroscopic fluid that absorbs water based on time rather that usage. So over time you end up with a higher percentage of water content. This lowers the boiling point and can promote corrosion in all parts of the system. The ABS module is full of lots of parts that are sensitive to corrosion and in Canada that module is $2400 (almost $2800 with tax). And three bottles of DOT 3 brake fluid only cost $24

Thats why even toyota recommends flushing it every 2-3 years. I used to do it with my sons help (operating the brake pedal) every two years during my spring switchover from my snow tires to my summers since I have the wheels off anyway.
Now that i added stainless speed bleeder screws on all four corners I can now do it myself in about 1.5 hrs which includes the time to jack up and swap tires as well. I went for the stainless speed bleeders since I have heard of many cases where the bleeder screws become so corroded they snap of when trying to open them which can sometime require replacing the whole caliper.

http://www.speedbleeder.com/size.htm


Brake fluid at two year vs new

 

To make it as expensive as possible lets assume I do a drain and fill every 30,000 miles . Since I have all the tools and an ultra gauge I can do it in my driveway for the cost of 4 quarts of WS and 2 crush washers. That would run me about $70 CDN. So in 300,000 miles that would be $700. I just did a quick search and someone can chime in with prices they have actually paid but seems to be in the range of $2500 US (maybe $3500 cdn) for a rebuilt.

Cant see how $700 > $3500(and that doesn't include installation costs)

Even if I had the dealer do it it would be $200 *10 = $2000. Still way less.....

And who are "they' in "recommend never changing the transmission fluid for a reason"

https://www.youtube.com/watch?v=RuNNqh8-jkw