alda like the wastegate have springs, that sag over time, so i could see them being part of "normal maintenence" but i could not imagine what kind of interval should be used.

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1996 s10 zr2 with a 6.5 turbo diesel
1996 c2500 suburban with a 6.5 turbo diesel
1981 300sd with a turbo 617
Monte carlo figure 8 car