Can i use Truffle oil that is 5 years old It smells wonderful

The shelf life of both opened and unopened truffle oil depends a lot on the storage conditions- but even under the optimum conditions, an unopen bottle is still considered only good for about a year or so. Five years, I wouldn't want to guess. That all said, the worst that happens to oil is that it goes rancid. It won't hurt you to eat rancid oil, but the taste and experience is not pleasant and it will ruin an entire dish. So the best I could say is you can taste it and see what you think it tastes like. Rancid oil will pretty well reveal itself very quickly. You might gag, and the taste could linger a bit- but you won't be harmed otherwise.

Have a look at this entry on safe and best quality durations (not the same). Check for off smell or taste. If none, probably ok.
https://www.stilltasty.com/fooditems/index/17809