Should you replace your SUNBLOCKS every year?

I have a ton leftover from last year... are they still good?Should you replace your SUNBLOCKS every year?
Keep 'em til the expiration date, BUT if you like left a bottle in your car and it was like 95 degrees outside...get rid of it. They can go bad if they are left somewhere it's too hot. The bottle I have in my cabinet is good for like 3 yrs...but I typically replace every summer anyway...just in case.
Just if you let it sit in extreme heat or if the expiration date on it is due.
They all should have an expiration date on each bottle. They can lose some of the effectiveness over time or if used past the date. Especially if they are used on a child or a fair skinned person.