Final answer:
The appropriate oil level in a standard transmission without a sight glass should be around one finger's joint below the fill hole, ensuring proper lubrication without overfilling.
Step-by-step explanation:
When checking the oil level in a standard transmission with no sight glass, the correct oil level should be within reach of a finger inserted into the fill hole.
This is typically around one finger joint below the fill hole.
The oil should not be above the fill hole level as this may indicate overfilling, nor should it be significantly below, as this could signal an insufficient oil level that can lead to transmission damage.