How long is it supposed to last? The 1FZ has the same issue as the 22R, cast iron block, aluminum head, so HGs just don't last forever like they did with an all iron engine. I figure this was early in the cycle of Toyota designing engines like that so they hadn't completely nailed down how to deal with different rates of expansion and the right materials. If you use OEM HGs and are careful about not overheating them it's just something you do every 150K. Seriously, though, so you do a HG every 10 years the engine will run for 300k, 400k or more without a problem otherwise.Ah yes, the regularly scheduled head gasket replacement.