I put lead additive on my gas for 69 mopar, but I that for the lack of hardened exhaust seats in my 906 heads.
Crappy, old rubber valve seals might allow enough oil to escape up and oil those guides for you. I don’t know about those old tractors, would some have bronze guides?
I don't know. I doubt it. I'd guess that the guides are just machined into the block.
