After a good night's sleep, woke up to see hows the belt color had change or not.
I shall let you see the pictures to let you decide.
What I did:
A thin coating of Obenauf's Leather Oil
As you can see, the color only darken A LITTLE BIT. The pictures looks dark but in actual it's only a little darker than the brand new natural leather you get.
After this, I will apply Obenauf's Heavy Duty Leather Preservatives (LP) and it will be good to go!