I guess this would go under DIY, well when i first got my car, something happened to one of the hoses with the previous owner, leaving it all discolored and nasty. Instead of buying a new one, i would try different things on it to see of it would clean up. Some cleaners had little effect and otheres sucked. I generally use things for other than the intended purpose, so one day when i had bought some leather wipes, i was like what the hell, and it was a dramatic result.

Before



After


As you can see the s bend hose looks brand new thanks to leather wipes.

 

Silicone lube will do the same. I hit mine when it looked a bit better then yours and it came out looking new.

 

Looks good but this is not a DIY so I moved it for you.

 

Hi Jorge!

It looks nice... for the black parts in engine bay I usually use Sonax car shampoo for cleaning, and then finish the plastics with a tire enhancer such as Black Magic or Tire Shine; after a couple hours parts are not so shiny anymore, but it leaves a deep black tone.

 

^^ Which is why you need to use something like silicone lube first. Silicone lube fills the pores and basically rejuvinates it. You can then put armorall on it and it will stay for weeks.