Well, I drained the trans and the nice-looking Amoco 90wt had a caramel foam on top. Filled it with NAPA 90wt mineral and after slipping out once a mile down the road it didn't slip out again on a 12 mile ride. Drove it again later and it stayed in 3rd the whole way. Hopefully the change did the trick. Think I'll dump the rest of that Amoco down a groundhog hole.
Good to hear that the issue seems to be solved. Additionally, any place that changes oil will accept oil used for maintaining vehicles or at least tell you where you can dispose of it. No need to dump it into the ground.
