No more than when the WH lining is compromised and it is rusty....
The key to anything is maintenance. If the expansion tank fails, assuming you have a closed system, the T&P is likely to weep. If you have anything on the ball, that should be a clue something needs to be done. Hopefully, you don't continue to drive your car when the pads are metal-to-metal on the rotors, or the tires are bald, or your exhaust has leaks...anything mechanical needs periodic checking and maintenance.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013
Unfortunately, seems most folks have forgotten that mechanical things break down.
I think it is because cars overall are so much more reliable than they were in the 70s and 80s. Even oil consumption has dramatically gone down with better metallurgy and fuel injection.
When I was growing up, you really needed to check your oil at least once a month or more, and it was extremely common for a car to need a quart or two to top-off between oil changes.
When was the last time you had to add oil to your modern car?
And Obama talks nice and sweet to the queen and doesnt rock the boat. The inspector is the queen, and if that queen does not like your attitude, you get screwed.
Thank god no queens here in the forum so we can argue a bit.
Well, on edit I forgot we have a king.... so have to be a bit careful after all.
More like a custodian. Always cleaning up the messes that the kids leave during recess.