Serta shortened their warranties in the past few years. They went from a long prorated warranty on select mattresses to a 10 year warranty. I was told that they wanted to better match what customers are told about how long mattresses should last. Some companies have maintained their long prorated warranties.
Truth be told mattresses rarely break. They do become uncomfortable. That’s not a warranty issue.
I had a foam mattress that became harder over time. It was old enough that a verified claim was useless.
Get something well made that fits your wallet.

quote:

Originally posted by frayedends:
It’s been a long time but I saw a video showing how much nasty sweat and gunk a memory foam absorbs. If no protectively cover I wouldn’t go more than 5 years. But that’s just a guess and because I’m ocd on cleanliness.

Gross! We have a Tuft and Needle Mint...not true memory foam...but anyway, we've always used a waterproof mattress cover on ours.
I hope that helps prevent the grossness you describe!