Check Automatic Transmission Fluid Level (Engine Running or Stop)?

When we measure motor oil fluid level, we have to turn off the engine. Automatic transmission fluid dip-stick has 2 marks: cold and hot. Some people say to take the reading while engine is running. Depends on the temperature of the engine, get the reading from cold or hot. Some people say to take the reading... show more When we measure motor oil fluid level, we have to turn off the engine.

Automatic transmission fluid dip-stick has 2 marks: cold and hot. Some people say to take the reading while engine is running. Depends on the temperature of the engine, get the reading from cold or hot. Some people say to take the reading when engine is off. Which one is correct?
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