Total oil capacity for the AW55-51SN is 8.18 qts. Dipstick difference MIN-MAX is 0.31 qts. Each time you drain the trans fluid, you only get to drain approximately 50% of the total capacity. Because the rest is inside the torque converter and other parts of the hydraulic system.
If you want to renew the trans fluid, drain it on a pan, making sure to capture all of it, measure and refill with the exact same quantity of new fluid through the dipstick tube. Drive the car for a couple days or approximately 20 miles to allow the new fluid to fully mix with the old one. Then repeat the cycle at least 2 more times.
For each drain and refill you’ll want to have at least 5 qts of new fluid and that will renew the existing fluid to around 50%. So, a quick math says:
1 time will renew the fluid to ~50%
2 times will do at ~75%
3 times will do at ~87.5%
4 times will do at ~93.75%
I think is not worth it to do it more than 3 times. Because you’ll be using almost 4.5 qts to get 6.75% of fluid renewed. Too smal of a benefit, to be honest.
After the 2nd drain and refill, you’ll need to reset the transmission fluid life counter with an advanced scanner or VIDA.
These cars use JWS3309 transmission fluid:
Examples are (from cheapest to expensive):
1) Toyota Type-IV ATF
2) Mobil-1 3309
3) Aisin Type T-IV (P/N: ATF-0T4)
4) Volvo 1161540 (very unlikely to be cheaper than any of the rest)
You could either take it to a shop, but make sure they use the correct fluid. If possible, you bring the transmission fluid .. DO NOT let them use a universal transmission fluid.
There’s a special procedure to check the oil level. These are the instructions copied from VIDA:
Oil Check Conditions:
The difference between MAX and MIN volume is 0.3 liters.
Check the oil temperature in the transmission.
At room temperature (+20 °C) the oil level is near the MIN marking on the “cold area”.
At room temperature (+20 °C) and low oil level the oil barely reaches the dipstick.
The “cold range” (+40 °C) is reached after approximately 15 minutes idling in the workshop, while the “hot range” (+80 °C) is reached after approximately 30 minutes highway driving at an air temperature above +15 °C.
Note!
Carry out the check at an oil temperature of +80 °C.
Go to car communication function group 4. Select the digital display parameter.
Select the parameter for the transmission oil temperature.
Preparing to check the oil
level
– Position the car on a hoist.
– Apply the parking brake.
– Apply the foot brake.
– Let the engine idle.
– Set the gear selector in position P .Move the gear selector through the various gear positions, stopping for approximately 3 seconds in each position.
– Return the gear selector to position P. Wait 2 minutes before checking the oil level.
Checking oil level
– Allow the engine to idle with the gear selector in
position P.
– Raise the vehicle. Remove the splashguard from under the
engine.
– The dipstick must be pushed down completely in the
dipstick tube.
– Caution! Wipe off the dipstick with a nylon cloth or similar. Do not use a rag which may leave lint or threads.