I have a 1956 235 straight 6 in my 1949 chevy truck and I was told to only run nondetergent 30 weight and clean with kerosene every couple of oil changes. I would like to run synthetic but was told the old motors don't like it.
What do you think about the Z-ALT additive? Snake oil or is it good for my motor?
Someone gave you some very incorrect information. Detergent oil and synthetics will be just fine in your engine. Leave the nondetergent for the air compressor or lawn mower. As far as the additive, snake oil. Just use a known quality motor oil, I use Valvoline myself, and you'll be fine. Most of the cam/lifter problems come from poor break in procedures, incorrect assembly, or improperly matched/poor quality parts.
