A timing chain will normally last the life of the engine and is replaced during a complete engine rebuild.
Pontiac Grand Prix does not have a timing belt. It has a timing chain and it is replaced when it breaks.
It does not need to be changed unless it fails.
never
If the engine has a timing belt, it should be changed around the 150K mark. If there is a timing chain, it does not have to be changed unless it is damaged.
Timing chains never need to be changed, only belts.
Every 80,000 kms
It has a chain with a cam gear and crank gear.
The timing chain is designed to last the life of the engine and is normally only replaced during a complete engine rebuild.
Should last the life of the engine and is normally changed during an overhaul.
Hopefully, never. I have 3 Jeep Grands with 253K, 203K, and 167K - none has needed a timing chain yet - all V8s.
I think they recommend to change it each 160-180K miles.
check your vehicle specs or do a web search. typically you are looking at 70-100k for most vehicles and if you have an interference engine, you will suffer top end damage if the belt breaks. If it a Grand Caravan it should have the 3.8L engine which has a timing chain which does not require replacement at a regular interval.