Gunk Aerosolve has worked best for removing any oily, greasy deposits on
engines,& transmissions.

Spray it on , let it soak, rinse it off.

Gasoline is also a great cleaner, along with kerosine.

All of the above will clean any engine squeaky clean, without scrubbing.

Brake cleaner evaporates much too fast to do any deep cleaning, and can
be an expensive proposition.

<<use Brake Parts cleaner...
I've found that "Brake Parts Cleaner" and rags with a bit of texture are
best for cleaning oily deposits off of engines.>>