Your description is real confusing but mixing new and old transmission fluid is not uncommon. Torque converters haven't had drain plugs for decades. The only way to get the old fluid out of them is with special flushing machines.
If it's not shifting correctly, that is a different issue. It sounds like someone already tried a flush thinking that was going to automatically solve some mechanical problem. The best approach is to let a mechanic at a transmission shop drive it and give you an opinion on repair cost.
Friday, June 22nd, 2012 AT 1:08 AM