The car has 120k miles on the original tranny. The harsh shifting occurs occasionally from 1st to 2nd gear only while below 3k rpm, anything above the gears will shift as normal. What's happening is that the rpm will kick with an increase about .2500 of an rpm or stall for a second before shifting to 2nd. My father who is a certified mechanic says my transmission oil is too thin and needs some kind of thickening lubricant added. Is this also a sign of transmission failure? I would like your inputs.