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Automatic Transmission Servicing


Automatic Transmission servicing is one of the most commonly ignored parts of a car when it comes to servicing and this is regularly the cause of failure, which can be VERY expensive to repair. Modern automatic gearboxes will outlast the rest of the car if they are serviced correctly but if they are not serviced and fail, the bill is likely to be between $4500 and $6000.

Servicing of an Automatic transmission requires specialised equipment as shown below. The reason being is that if you simply open the plug in the bottom of the gearbox you will only get about 30% of the oil out as the rest is trapped in the various parts of the gearbox.
The cost of servicing them with us is between $230 and  $300, depending on what size the gearbox is and if it has to have a special oil. (Please see Price board).
How we assess the condition of your Transmission Fluid 
A sample of the fluid is taken from the dip stick and put on a white sample pallet. The photo opposite - shows :-
  • Top – a typical Auto transmission that needs servicing.
  • Middle - a Transmission that is in desperate need of servicing.
  • Bottom – New Transmission oil
 The colour is then compared with what new oil looks like. The range is shown below.
at fluid test(copy)
New Fluid       Fluid ready for change              Overdue for change                 Very serious condition
We test the fluid every time your car has a WOF or Service and report the result to you on the Preventative Maintenance Report sheet.
We are often shocked by the condition of transmission oils that come to us after being maintained by other garages.
Auto Trans Servicing

The Automatic transmission Machine hooked up to a car

What we do and why

We initially add a Transmission flush solution (you can think of this as a detergent) to the gearbox oil and take the car for a short drive, ensuring that all the gears are used.  This softens all the dirt in the gearbox and gets dissolved in the oil.
Then our dedicated automatic transmission Flushing machine is connected into the transmissions cooling circuit so that the fluid is now running through our machine, and back into the car.  The circuit is then blocked off and the old oil diverted out of the car while new oil is pumped into the car. We will normally pump between 8 and 11 litres of new fluid into the car during the process and then leave the oil pumping though the machine for a while which filters any remaining dirt out.
Finally a conditioning fluid is added to the new fluid which helps soften any rubber seal internally and seal up any leaks that may occur in the future.

If you would like the delux service, we can also remove the gearbox pan and replace the filter and seal. This would add about $45 to the basic cost for your car. This provides extra protection if dirt enters the gearbox, something fails in the gearbox or if it is not serviced in time the next time.

WYNNS-Logo 300
We use Wynns Specialist Flushes and treatments in all our servicing.
AT image 3(copy)

This shows the dirty oil on the left coming out of the car and the new oil on the right being pumped in.

The Risks 

If your gearbox has been serviced there are no risks at all with this service. If however the oil condition is poorl it is possible that the dirt is" holding it together" and if we remove it the transmission may fail. It may have been about to fail anyway. In this case it would be wise to just change the oil and not give it a clean out, and we would discuss this with you if we felt there could be a risk.

A Final Word

If we service a very overdue gearbox in some cases due to the huge amount of dirt in the oil, a small amount of it will not come out, which will make the new oil look a bit dark. In these cases we will keep the fluid running through our machine for about half a hour so the filter in the machine can remove as much of it as possible. The new oil will still last the 40 000 to 50 000km, and the result when it is done the next time should leave a much better result.




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Gleniti Auto Services 2022
356 Wai-iti Road