Engine oil in the automatic transmission line

A significant amount of engine oil was added to my automatic transmission line. I drove the car (2010 subaru forester) for about 10,000 miles. I noticed the transmission slipping. I brought it to the dealer. They found the engine oil in the transmission, flushed and replaced the fluid. The question is How badly is my transmission damage. The warrenty is now voided and I am afraid that I will need a new transmission fairly soon. Please help.
thanks

What year?
Is this a Continuously Variable Transmission?
How is it operating now?
Did the dealership give you any insights?

Your transmission is undobutably damaged, if the party that added engine oil to your transmission can’t be held responsible, you have to decide wether to do an early trade-in or wait for a tranny replacement. No one can tell how much your tranny was damaged, short of a tear down.

Thanks, a cheap oil change place did the damage. As oldtimer11 indicated, the dealer indicated that there is no way to tell how much damage was done. It is operating now, seems fine, but I think I am sitting on a time bomb. it is a 2010 subaru forester with about 40K on it.

It’s unfortunate that you went 10,000 miles with it. Had you realized it sooner, I would have suggested getting everything documented and pursuing a paid for extended warranty from the quickie lube place. You could still try, but it might be too late.

Meanwhile, you might get lucky. It might last forever. One never knows for certain.