I got 105k miles on original spark plugs when to change them?

I have a 2004 ford mustang 3.8 v6 and i bought this car 5 months ago with 97k miles on it and the spark plugs are still original i was curious as to when to change them money is a little tight at the moment can i still hold off maybe another month with them?

They likely show some wear. New ones, properly gapped, are likely to improve fuel mileage a little bit.

Factory recommendation is at 60K miles.

Check your owners manual and maintenance manual for recommended maintenance intervals. Follow the schedule and you will be fine. 100K on modern plugs is not out of the ordinary.

It still runs? Wow. Go for 200,000.

You are way over-due. Your car came from the factory with Motorcraft PLATINUM spark plugs which are only good for 50,000 miles before the gaps start burning too wide overheating and ruining ignition coils.

For some strange reason Ford didn't get in the iridium spark plug bandwagon when other manufacturers did. If they would have the spark plug gaps would still be.054. Measure your spark plug gaps when you remove them from a COLD engine.

Motorcraft ignition wires are terrible! They gain electrical resistance @ 50,000 miles. Taylor and AC-Delco ignition wires are much better.