Phone 1-250-765-9452

Dipstick verses transmission cooling line fluid exchange procedure

Looking at the transmission fluid to determine what percent of it was changed is neither scientific nor accurate. The only way to properly assess how much has been changed is to test the fluid before and after the exchange with laboratory tests.

The test consists of three samples. First sample is taken of the fluid as-is. Secondly, a small amount (5 oz.) of a tracer element is poured into the transmission. The vehicle is then ran and taken for a short drive (about 15 minutes) to assure total mixing of the tracer element with the old transmission fluid. The second fluid sample is then taken.

Thirdly, the fluid exchange is them performed as per the equipment manufacturers’ recommendation. The third fluid sample is then taken. At this point, the samples are sent to a lab where they test the first sample to determine if there are any properties present of the tracer element. The second sample is tested for parts per million (ppm) of the tracer element. The third sample is also tested for ppm of the tracer element. At this point simple math will determine what percent of the fluid has been changed. The tests that were performed on a transmission dip stick style fluid exchange machine using extra fluid as per manufacturers’ recommendation did not show better than 52% new fluid.

The test personnel determined that although manufacturers of the dip stick style exchange machines recommend using 15 % to 30% more fluid when using this method, acknowledging that it is not as effective as a cooling line exchange, it is not a sufficient quantity in order to obtain a satisfactory exchange. As the dilution of the new fluid increases to 50%, it requires twice as much new fluid to replace the old fluid because at that point, half the fluid being changed is new. If double the amount of the transmission capacity had been used initially and new fluid managed to get to 65%, at this point further flushing is only changing 35% of the old fluid because 65% of the fluid being pulled out is new. This dilution/percent changed factor is why the first half of the fluid capacity is relatively easy to change but to change the second half of the old fluid will require a tremendous amount of fluid using the dipstick exchange system.

The personnel concluded that if the dipstick method of changing the fluid must be used, a minimum of three times the entire (not drain and refill capacity) of the transmission fluid must be used to obtain what could be considered a reasonable percentage of the transmission fluid.

For more information on any of our products, please get in touch

Email Address:  

Fluid Service Technologies
816 Ellery Street
Victoria, BC, Canada, V9A 4R7

3034 4th Street SW
Calgary, AB, Canada, T2S 1X8

Transmission Flushing Machine
Engine Coolant Machine
Parts and Accessories