We are usually asked ,
Should I have my transmission flushed ? and will this count as a service?
Well 2 different things really… When performing a transmission flush one way of achieving this is to disconnect the return transmission cooler line and while adding the correct type of new fluid to transmission have the vehicle idling in park. In some cases in Neutral or Drive pending how cooler flow is set up on a particular transmission.
Once fluid exiting the cooler line turns to the new fluids colour you know pretty much it is just about clean but not totally clean. Clutch frictions act as sponges so some minute oil traces are still within the transmission. This will eventually be released when driving starts and oil is squeezed from the friction plates.
Only thing remaining now to complete flush is to remove transmission pan and replace oil in pan, the filter & pan gasket.
Were is the difference in service v flush you ask.
With the service you only get to replace the fluid that is contained in the transmission pan, amongst the pan gasket and oil filter as performed on the last step of flushing.
In short the service will successfully drain about 30 % of the transmission fluid, a further 15% if the trans is an underdrive type were the flush can replace up to 95 to just under 100 % of your fluid.
So … should you have your transmission flushed??? And will this count as a service??
Flushing can upset a sensitive weak transmission, as from serving life with its old oil it now has to adapt to totally different fresh fluid. In this case new may not mean better. Kind of like a blood transfusion, as funny as it may sound.
A service may be the best way in keeping this vehicles transmission on the road longer.
As there are other methods of flushing a transmission, a particular way of flushing which in my opinion serves very little purpose as far as maintenance is concerned is the flush machines. While using these machines the operators are advised to simply suck out the old oil and fill with the new.
Hmmm, what happened to replacing the filter and inspecting the pan. Not a fan.
Hope this has enlightened you of what can work and what can be unhealthy for your transmission