So my dad just finished replacing the ATF and now when we put the car into gear it takes a noticeable amount of effort to change in between. I was wondering if this is normal, considering the fact that it may not have been changed at all previously.

Side note, someone recommended adding some lucas liquid because adding new ATF may cause some slippage. So he did

Thanks for the help. SOrry if posted in the wrong forum.

Double check the fluid level as prescribed in the owners manual or FSM. Low fluid is often the main reason for delayed shifting.

changed because it was very dark ? how many miles on the trans ?

now it is a flare shift struggles to up shift ?

what ATF was used ? you drained it or flushed ?
need all the info