, it doesn't cost a lot to fix. it is just a simple matter of draining the fluid and refilling it back up. depending on how much is in there and where and what was poured in. you might not even need to change it out.

Where were the two types of lubricants mixed, engine or transmission. How mush of the the two lubricants mixed, number of ounces.

Where in the motor or Transmission are they mixed? Both are lubricates so that is good but they have very different properties. Transmission oil is not as thick so if you put motor oil in the tranny it may burn up a pump and run terrible. If you put tranny oil in your engine then it will not lubricate properly and will eventually freeze up moving parts. Flush and refill as quick as possible.

If transmission oil was mixed into the engine of your car, truck, motorcycle, quad, or moon rover, no problem but an oil change should be done soon. If motor oil was mixed into the transmission, see a transmission specialist. If they were mixed in a drain pan for recycle, that's okay.

Is the mixture in the motor or the transmission?

Year, make, and model?

If you don't include the above basic information, no one can tell you what the potential problem area is/are nor the costs you may be looking at.