The oil level is low.

Add oil in order to acquire the proper oil level. Refer to Transmission Fluid Check .

Air is leaking at the intake tube due to a damaged O-ring.

Replace the intake tube seal and filter.

The oil pan filter is clogged.

Replace the oil pan filter. Refer to Transmission Fluid Pan and Filter Replacement .

The oil is aerated.

Make sure the oil level is correct. Refer to Transmission Fluid Check .

The external oil filter is damaged.

Replace the external oil filter. Refer to External Transmission Oil Filter Replacement .