My friend recently bought an 08 tsx engine to put in his 07 civic si. However the engine he got too much sludge says the mechanic. I'm not too familiar in what's considered too much, but what do you guys think and what should he do?

 

It does look like the engine was neglected, probably didn't do regular oil changes. Here are some pics of my sister's 97 BMW 328i when I replaced her leaky valve cover gasket. You'll be able to see the difference right away.






See how clean everything looks? No brown residue coating everything in sight. I think that's why your mechanic said not to use the engine.

Sorry about the pic quality, I took them with my cellphone.

By the way these were taken at 195K miles.

 

sadly i have seen worse... there is some sludge but not something that will be a deal breaker... does your friend plan to tear down the engine for cleaning before install, or was he just planning to drop it in??? if just dropping in, there are a few cleaners that can safely and slowly clean up those internals... then run a good synthetic oil...