Back to your question about LIM gaskets. AFAIK there'* no true way to avoid changing them. We have found that no matter what coolant you run they usually go bad.
Once in a while (not often) someone pulls their engine apart and the gaskets look new while they have 100+K miles on them. It'* infrequency keeps us suggesting the swap out to the GM version aluminum framed ones.
that depends on your mileage lol at 300,000 yes... 60,000 not really... my only leak is a small crack in the top driver side of the radiator plastic tank, leaks under pressure... and the oil pan gasket... will replace next oil change... realised it was leaking during the last oil change and didnt have a way to get to the store to get another gasket lol