I read on here that someone said to help prevent it is to change your coolant regularly with oem toyota coolant as there could be composition change in the old coolant causing a premature head gasket failure.

I changed my coolant a few months ago with oem Toyota coolant and I'm at 50k miles. Just playing it safe.

I also read that if you go to the Toyota Parts department and buy a head gasket from them it will be different than your original. There was a redesign in the head gasket.

What I want to find out is when did this head gasket redesign take place? What year 4runners have this updated redesigned head gasket? Or did this update take place after the 4th generation production?? That would mean we all have the "old style" head gasket in our 4runners through 2003-2009 years. Would be very interesting to find this out!