I suppose, without the poster coming back in here ,and saying how long,and how he actually did the clean job.WITH what product..It`s only speculation that the engine is JUNKED..If he just brushed the cleaner on, and then, took it off somehow within 10 mins.,and it stayed GREY...As apposed to letting it sit for 3 days with the cleaner on.WE don`t know if he used a BASE ,or ACID base, type CLEANER either..THERE`s too many variables,to just out,and, out ,say the engine is trash."THE trash the engine" response may be correct.BUT with out knowing more, we are all guessing..