when should you change timing belt for a chevy impals ls with a 3.8L?

You should probably change it around 100k. Whoever said it doesn't have to be changed as long as you change your oil is crazy. You will know when it is starting to go bad because it will start to make a noise from that part of the engine. Getting it changed at 100k, if it hasn't gone bad, is a great preventive measure. The alternative is, if it breaks while your driving it will cause bent valve is the engine which means you will need a rebuilt engine. <- Much cheaper to change the timing chain. Hope that helps.

If you look in your owners manual it gives you the specs on when everything needs to be changed.

I would guess it doesn't have one. The GM 3800 engine has a timing chain and if you've changed your engine oil regularly, it doesn't need changing unless you have over 250000 miles on the engine.

I would say 100k. If you have any doubts, just do it, the alternative is expensive. What leads you to believe you need to change it?

THIS VEHICLE DON'T HAVE A BELT