First put into production in 1969, the TH350 was hailed as one of the best transmissions to be designed. That status did not last long as it was phased out by 1982 and possibly 1984. No matter the short run, this transmission made a strong impact on transmission development
Since this is an older transmission, the amount of transmission fluid it needs to work is about 4 quarts. That is unless the torque converter is empty. The size of the converter would determine if you added an extra 2 to 5 quarts of fluid when changing it.
To learn more about this transmission and its fluid type, just continue to read our article. It has the information you want to know about so you can get the right fluid for these older transmissions. It is still going strong after 50 years of service.
The consensus is that the TH350 transmission only needs 4 quarts of transmission fluid to run like it was designed to run. But that is if you are only changing the fluid in the pan.
There is more transmission fluid in the torque converter and if you give it enough time, that fluid will drain out as well. When it does you will have to add more than the four quarts of fluid already mentioned.
The torque converter was designed in several sizes and the 7 & 8-inch models only needed 2 extra quarts to run. The 9-inch torque converter needed 2.5 quarts, the 10-inch needed 3 and the 11-inch needed 3.5.
But the size of the torque converter did not stop at the 11-inch length. There was a 12 and a 13-inch model that needed 4 & 5 extra quarts respectively.
The transmission fluid capacity for this model of transmission ranges between 4, 6, and 9. It all depends on the size of the torque converter. 4 is for the pan alone but if you want completely fresh fluid inside your transmission, then you needed to add 2 to 5 quarts extra to do all the necessary lubrication.
The thing to do when you go to change the transmission fluid is to determine if you just want the pan fluid or all of the fluid. If the latter, then you need to wait sometime before it all drains out.
Once all the fluid is out, make sure to change and drain the filters to make sure you have no old fluid inside the transmission casing. Then make sure the new filters are in and everything is buttoned up tight before adding the new fluid.
This will depend on the year your transmission was made. Some people swear by Type F as it was used in FORD vehicles with the TH350 transmission. But this fluid is only best for those models built before 1980.
Next up will be the Dexron III and it is probably perfect for older TH350 transmissions. It is completely backward compatible with Type F fluid so you can interchange but not mix the two options.
Dexron VI is the latest Dexron version of transmission fluid. It is possible to use it in older TH350 transmissions but the results may not be as spectacular if you used this fluid in more modern versions of the TH350.
Dexron VI is made for more modern transmission and while it has some backward compatibility, that is not so for some older transmission models. If you are not sure which one to use, check your owner’s manual to get the best information.
It is possible to use Dexron VI in older transmissions. And while this type of fluid is backward compatible, it has its limitations. It is not the best option to use when you own an older TH350 transmission.
For this model of transmission, you want Dexron III or Type F fluid. Especially if your TH350 dates to the pre-1980s era. The best brands will be AC Delco, Valvoline, and Catrol.
Some people suggest that the synthetic is every bit as good as the conventional transmission fluid. It will be up to your preference and budget which one you buy.
TH350 transmission fluid specs
|Name||Method||Units||ATF- Dexron III|
|Density @15C, relative||ASTM D4052||G/ml||0.861|
|Appearance||Visual||-||Clear & bright|
|Viscosity, Kinematic 100C||ASTM D445||mm²/s||7.9|
|Pour Point||ASTM D97||°C||-42.5|
|Viscosity, Brookfield @ -40C||ASTM D2983||mPa.s (cP)||17.600|
|Viscosity, Kinematic 40C||ASTM D445||mm²/s||32|
|Viscosity Index||ASTM D2270||None||186|
These specs were taken from this link. They are for the Castrol version of the transmission fluid. You would need to look for the specs for other brands independently.
If you want it to last, then maybe change it every 2 years or 20,000 miles. Some owners are under the impression that you do not have to change this fluid at all.
The way to tell if the fluid needs changing is by its color or smell. If it smells burnt or the fluid is a solid color then it is time to change the fluid. Or if you hear a whining noise coming from the transmission. Then it would be time to make the change.
Dirty fluid clogs up the gearing, etc., and won’t let the fluid flow so it needs to come out.
These older transmissions are simple to work on. They do not have all the modern parts and accessories to worry about. All you have to do is drain the transmission and put the plug back in. Then add the necessary amount of fluid to top it off.
The only change in that process would be if you would want all the older fluid out. Then you would have to wait for the torque converter to drain and buy extra fluid to completely fill the transmission.