320k on my 12v. Only run delo. No blow-by and everything is clean inside. Oil is still reasonablly clear @ oil change.
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97 3500 4x4 Auto, Goerend Tranny & TC, 15* timing, #10 plate full forward, autometer gauges, lock up switch, prime loc, Amsoil Nano, straight piped, posi-lok, lots to come