Trans fluid getting into rad causing overheating

Check your coolant for any trans fluid mixing,& ck the trans fluid for coolant, the radiator may have an internal leak (trans/ coolant), If they are mixing within the rad, radiator needs replacement. If OK then there may be 2 separate problems. The cooling system may need service or the rad is rusted and there is a separate trans problem. Ck for fluid mixture first!

Engine overheated? Which also affects transmission oil temperature - trans fluid is dark and smells burnt? You have probably toasted friction surface (I think it would be a band) that applies reverse. Internal problems requiring repair. About the only thing you could do is change the fluid and filter - add some "Trans-X" as part of the replacement fluid. It may or may not work. Severe overheating of the transmission oil does usually cause internal damage to a transmission.
Let me know if this helps you at all

check your level of trans fluid if low fill then check air hole on top of trans and make sure it is unblocked...if they get blocked it will cause your trans to overflow your fluid causing loss and overheating you fluid causing light to come on...the air hole is usually a rubber or plastic tube sticking up at least 8 inches from the top of the trans

this oil is usually from the trans cooler in the rad that helps keep the trans fluid at operating temperature by the engine coolant absorbing the heat from the trans fluid .the cooler is a steel tubing in the rad tanks that the engine coolant runs around and absorbs the heat.when the cooler rusts through the trans oil seeps into the coolant.if it was motor oil it could be caused by a head gasket were the oil passage is next to the coolant passage in the gasket and it seeps into the coolant passage.however the coolant pressure is alot higher than the oil pressure and the coolant usually enters the crankcase.

The transmission and engine are there own entities. Unfortuantly the radiator in some vehicles cool the tranny fluid. Its possable when the coolant lines were disconnected from the transmission or from the radiator, the seal was broken on the radiator where the line goes in from the radiator, so you wont see it because its internal. This will allow trans fluid to enter into the radiator. Be careful with trans fluid mixed with the coolant may cause engine damage. Your solution to the problem if this is infact the source would mean replacing the radiator, if you do this be sure to flush the coolant system to rid trans fluid.

Are you sure it is oil and not just old corroded dex cool? Just asking because about the only way to get oil in the radiator is through a bad head gasket or cracked head which will usually cause the vehicle to run poorly. Here is a few pics of what dexcool can become.

If it was overfilled this could happen. Check the level according to instructions in your owner's manual. If it is overfull, remove enough to get it back to the correct level. Overheating will cause the fluid to expand but unlikely it will leak unless it was overfilled. I would suspect too much fluid was added.

(inside the radiator.) trans fluid flows thru a line in to the bottom of the radiator. to keep the trany fluid cool. if that line is corroded inside the rad,coolant will get into your trans, check your trany fluid to see if it has coolant in it. if you do change radiator and flush transmission, note: if it is, the odds are the transmission will not function properly even after you have had it flushed.

oil cooler in rad clear??could have overheated with a blockage in the pipes or rad??

unless someone put trans fluid in your engine oil
the only place that it even has a chance is in the radiator
you will see the trans lines running in and out of the rad.