water getting into oil in my 4.3 engine

i have been told that is a common problem on the 4.3 engines. i have 88 s10. i thought it was a head gasket, but have not fixed yet. i used liquid glass as a temporary fix.

it seems to fix for about 2 years and i do it again. I was told other day someone said i would guarantee you its an intake manifold gasket instead of a whole head. is the 4.3 bad at having that as a problem? any experience with that? i would rather spend 15 dollars on intake manifold than the whole head gasket set. I know i didn't do the liquid glass right but still helps. it said I'm supposed to flush radiator and run it hot with water first. i just poured the liquid glass into radiator with thermostat open. will that hurt anything? seems to have fixed problem for now.