well they had wierd timing curves combined with 87 octane fuel, they never liked that.

and its not actually the head gasket that ALWYAS goes on them, but it does go alot. they have another problem of having the tensioner wear out and wear through the front cover, and that is what mixes the coolant with the oil 90% of the time.

the oil / coolant separating o-ring on the front cover also blows out for some stupid reason and the mixture happens there as well.

combine that with a head that isn't torqued very well from the factory and you get a motor taht wasnt mean ' in absolute stock form' for lots of performance. oh wait, it was discontinued after two years in the 240. haha. so nissan figured that out.