The oil filter on the TTA screws into the metal piece that the coolant flows through and that screws into the next metal piece that is attached to the block I think. Where this screws into the block there is an o-ring, what is this part # if it is still available? Does anyone know. Changing the oil and removing the filter ended up with this little o-ring coming off too. It seems ok now but I would like to be prepared with a spare if possible. Thanks.