Foam in transmission question

Hello, I recently took my blazer on a road trip (300 miles) and noticed a lot of transmission spray on the trailer I was pulling. I checked the transmission fluid and found it to be quite foamy. It was full or a lil over full still, even after the trip. Earlier in the day before I went on the trip I had Walmart do its regular oil change, the paperwork doesnt show any tranny fluid being added. I have a feeling the spray was coming from a overflow weep hole, but havent confirmed the source of the spray yet. Anyone have and idea what would cause foamy tranny fluid?

oh ya, my blazer is a '97 4x4...4 door

The cause of this problem is old fluid fliuid gets burned and starts breaking down. Change your trans fliud and filter.. Having your transmission flushed would prob. be a good idea.

Tranny fluid foams when it has air whipped into it (thats why its called foam) It gets air whipped into it by fluid getting into the geartrain. You have a 4L60E tranny, which does have a vent from the top of the case.

There are two ways to get the oil into the gear train: overfill it. overheat it.

You can overfill a 4L60 by at least 2 qts b4 you hit the gear train so I suspect a combination of both.

I had a Turbo 400 do the same thing to me pulling a stock car up a 5 mi. grade on I80 just before it blew. The fluid wasn't burnt or over full. If you tow much w/ a heavy load you may be looking at the same thing. Good luck.

I had the same problem the fluid and filter was changed at 100k and does not seem to be overflowing.