motor blow by

[lovemybird]

i have a restored 66 bird with a 390.has about 1000 miles on it. i went to change the oil and used mobil one synsetic.big mistake!!drove about 50 miles and car started running rough.opened the hood and saw alot of blow by.got car home and changed the oil to 10w40 and a new filter and plugs.sounds like rings weren't set yet.ben told to drive it for awhile and see if rings set.was also told to try adding lucas break in oil to it.hope i didn't ruin something in the motor.anybody else here of this problem?

[Gary Tayman]

I'm a bit curious as to WHERE you got your motor.

Indeed, synthetic oil should not be used when breaking in a new motor, but is that the real problem? Did you drive the car 1,000 miles before changing this oil?

My 64 390 has blow-by, was told to drive it hard for the rings to seat, but four years and several thousand miles later I'm still waiting. It was using a quart of oil about every 50 miles; now it's around 100-150. About the only thing I've been doing is putting up with it -- until such time as I get rich and can buy another motor, calling this one a total loss.

I've heard of the trick of pouring Bon-Ami into the carb, haven't had the gumption to try it. I guess the big worry is making it worse.