2005 Grand Prix GT: How many miles should i wait for until I get the transmission fluid flushed and replaced?

Question

Mine has just over 37,000 miles. Thing is that a guy who owns a transmission shop owes my dad some money. He will deduct the cost of the transmission service from his debt with my dad. Therefore, it is free of charge for me, so when should I take it in?

Answer 1

If it has never been done yet do it now. I change mine in all my trucks every 25k and cars every 30k

Answer 2

  transmission fluid  for what  i  know you can flushed it 150k .and  change the filter too. to flushed  and change filter can cost  you including the labor 150 to 200 dollar.if you know what to do

you can do it your self. it cost  nothing  

Answer 3

i'd change it every 100k miles