[Udi]

Need regular maintenance?
Or once?  For at least a year?
Need to use once every few months?

https://www.amazon.com/Solution-Finish-Black-Plastic-Restorer/dp/B006NZQ3T8

[CraigB]

Is this for your interior door trims you've just done   that black plastic restorer is for exterior use

Some of the interior cleaner/protectants on the market will blacken interior trims, the Optimum protectant I use does    Optimum Protectant Plus 504ml | ZAS Automotive | Go To Shop

I think Meguiar's also do something similar, or you can buy interior trim paint and do them again

[Udi]

Is this for your interior door trims you've just done   that black plastic restorer is for exterior use

Some of the interior cleaner/protectants on the market will blacken interior trims, the Optimum protectant I use does    Optimum Protectant Plus 504ml | ZAS Automotive | Go To Shop

I think Meguiar's also do something similar, or you can buy interior trim paint and do them again

Yes is it for the dashboard doors for how long does it hold work?  For two weeks?  Or for a few good months?

[CraigB]

I do the interior treatment every 3 or 4 months.

[Udi]

I do the interior treatment every 3 or 4 months.

Is bad?