I've been playing around with different engine cleaners and dressings the last few years. I've used a hose to clean my engines for 20 years without an issue. Going forward, I'm considering using the Tornador Air Gun and an air compressor for engine detailing. I recently used it and it worked extremely well. It's hard to beat using a hose/water (carefully), but this is probably a close second and you don't run the risk of hitting any sensitive electronics. https://tornador.us/z-014-tornador-air-gun.html
I need to get an air compressor next.
A friend gave me Infinity Wax Rubber Wax (the updated formulation) to try. It goes on extremely well. Very even. It's very hydrophobic and great for anything plastic or rubber. The downside is it's time consuming. Will take much longer to apply than using a hose/dryer and a spray on dressing.
These photos are a bit dark due to lighting. This stuff leaves a really nice matte finish. No stickiness at all. I really like it. I'll be doing the Subaru next. I've only hosed off the Nissan engine once (shortly after I first bought it), and have since just maintained it by hand. Took the truck to the beach this past weekend and the engine bay had a lot of sand in it. I used the Tornador Air Gun and it cleaned it up well. An air compressor is a must for me. Sand is a PITA.