If what you see in the tank is a mixture of coolant and ATF, immediate rescue is needed. If there is a leak in the ATF cooler, which is inside the radiator, water/coolant can get into the tranny, and it's ruinous. The fix is a new radiator and a tranny flush. This works only if the coolant hasn't damaged the tranny.

Some head gasket breaches allow compression pressure into the cooling system at cold start-up, but the breach closes up when the engine is fully heated. BTDT

Here's a quick test. With the engine cold, open the hood, remove the coolant reservoir cap and positioning yourself so you can see the reservoir. Start the engine.

If you see coolant welling up and out of the tank, it's a head gasket problem.

If may be that you can replace the cap and drive like that for a while. Just watch the temp gauge often and if the needle hits the red, shut down ASAP. Carry some distilled water in the car to top up the tank wherever you are.

Run the compression test, too. It is a more accurate test. Also look for white exhaust (actually steam) before the engine is heated. Plan for a head gasket replacement soon.

Goo Luck,

Bob

:>)