If dinosaurs lived 65 million years ago why does our oil date to be 100 million years old.?

A fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms, containing organic molecules originating in ancient photosynthesis that release energy in combustion. Such organisms and their resulting fossil fuels typically have an age of millions of years, and sometimes more than 650 million years.

Carbon based life forms of all kinds contribute to petroleum deposits.

Oil comes from the broken down remnants of plants and microbial life.

Thank you to every person that tried to give a courteous answer. 

We don't get oil from dead animals but from thick vegetation that covered several parts of the globe long before and during the time of dinosaurs. Fossil fuel is the results of dead plants that didn't decay because of the lack of oxygen for bacteria to live in to consume them.

Well, Jesus, you are wrong.  Oil does not come from dinosaurs and no one that knows much about anything makes such a claim.  Animal life is a small portion of the total mass of life on earth, so clearly, animal life (and especially only a small portion of animal life) is not going to be all that important a contribution to residuals from death of living things.

The chemistry of oil indicates an origin through burial of plant matter, for the most part, and not complex plants, but simple plants, algae, plankton, and similar. Single-celled organisms dominate life on earth.

"It's called fossil fuel because it's supposedly came from the decay of the dinosaurs"

No, it is called fossil because it consists of the fossilised remains of plants and animals

Dinosaurs spanned a wide time frame.  

Coal and oil are also largely from trees - vegetation.

And while dinosaurs became extinct around 65 million years ago, they did actually exist for rather a long time before that...

DIno Saurs  lived 200- 300  millions before too kiddo.