Originally Posted by jm1234
The only system I know of with both fluids (that you would change) and a filter is the oil. The cost of the oil is probably in the range of $5. Why not ask them to change the oil too? I think they would do it anyway.
$9/liter (TWS 10W60) x ~8.5 liters = $77. I would not be concerned about the small amount of oil left behind in the old filter. Just change the filter.