There are several ways to clean the engine from carbon and unwanted deposits and I like this one:
engine cleaning using water
YouTube - Civic Water Steam Cleaning Engine Part 1
YouTube - Civic water steam cleaning engine 2
YouTube - Civic water steam cleaning engine 3
YouTube - Civic water steam cleaning engine 4
Karon lang ko kakita ani nga video pero kasulay na ko sa ing-ani nga pamaagi sa pag limpyo.
It doesn't stop there, mas maayo pa gyud kung permi ing-ani while nag dagan, idungan ang tubig with gasoline, wala gyud usok sa kadalanan ug wala pud engine knocking nga mahitabo.
Now, what if you'll mix clean water with your engine oil?

The only way to find out the result is to try it yourself.