Im pretty sure theyre just fuckin with ya... You cannot use multiple block guards and yeah i gotta say for someone to be trying to get real useful info, and have people making it humorous and misleading someone by joking around with them, is pretty fucked up... but to answer the question you can only use one block guard and it is best to have it pressed in by a machine shop because they have to resurface the block to make it perfectly flush so u dont have head gasket sealing issues.....

and oh yeah it kinda gave it away when the said to use CRISCO to get them in.....