True confessions: Many years ago I had a '68 Chevy with a very tired 307 that went through a lot of oil. At one point I did add some gear oil, thinking that 75W-90 would be way thicker than the Quaker State 10W-30 I usually used.
Consumption continued unabated at about a quart every 75 miles.
Water under the bridge, but I wonder whether a 20W-50 would have helped.