Your 6 may be leaking a lot of that consumption.......as well I've used Castrol 20W50 since the 70's in all my street muscle cars and still do today.....I also will put 1/2L Lucas Oil Stabilizer in. Lately I've added GM's EOS for durability as it still contains ZDDP. Nailhead is right about the valve guides, etc.........all this wears and as some of old timers remember these cars leaked and used oil when they were new. As long as it's not burnin' blue smoke.....you're doin' OK.
cheers BJ
__________________
......big block, 4 speed, bench seat, it doesn't get much better
