I bought a timing belt for my 1999 Si 2 years ago but didn't get around to installing it. I want this to be the last timing belt I ever install in the car, and I plan to keep the car for years to come (the current timing belt has been in there for 11 or 12 years, but only has around 68,000 kms / 42,253 miles on it). Would the 2 years the unused timing belt has been sitting around have degraded it a bit, made the plastic harder? If so, I think I should just buy a new one when I'm doing the installation job.

 

Unless it's been sitting outside in the elements, I wouldn't worry about it. Just make sure to visually inspect it to see if it's frayed or cracked.

 

It was sitting in my room for a year or two, and then I moved it into my garage where it's sat for another 6 moths to a year. If that takes 1.5+ years off its usable lifespan I'd prefer to buy another one to install.

 

Just use it. The new one you buy may have been made 2 years ago.