Q: Transmision has black oil, had Line a grinding noise and Line a whistle

If the check engine light is on, there will be stored trouble codes and those will provide clues to the mechanic as to what is going on. Transmission oil color is not always dispositive of a fault but if the transmission oil is really black, and/or has a burnt odor, then that probably signifies some sort of internal failure. To get a speedy resolution to your issues, the recommended service is a check engine light diagnostic. If you request that service, the responding certified mechanic will read the trouble codes and then test actual parts, that is perform a diagnostic, to find the fault and get the problem pinpointed. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.