I use olive oil. Put plenty on and leave for a bit then buff up taking the excess off. Good for a year +.
I also have turtle wax black plastic restorer which is ok but it dries out too soon whereas you need something oily to absorb into the plastic.

Always found "Forever Black" to be very good.

Cheers
Col

I decided to paint mine as a permanent solution...

https://www.rrsport.co.uk/forum/topic53714.html Kev

MY2014 L405 RR Vogue SE 4.4 SDV8 in Corris Grey
MY2010 L320 RRS HSE 3.0 TDV6 in Stornoway Grey

Painted mine with pick-up truck bed liner........

hasn't cracked, peeled or faded since doing it. Plus side is the bed liner has a very slight metallic black look which goes well with the car.

I will try to get a picture and post it up later. Should add with suitable masking i only needed to remove the wiper arms and whole job took about 1/2 hr. 2006 RRS HSE 2.7 TDV6 (The Baby one as I keep being told)
1999 Discovery 4.0 V8 (Gone but not forgotten)
1997 Range Rover 3.5 V8 (Long gone now)
1966 Series II SWB with RR 3.5 V8 (Never finished, now sold)

I decided to give mine a little spray with some satin black plastic paint in aerosol and it worked a treat looks just like new.

I masked the rubber strip edge that seats on the windscreen, then took the wipers off masked the stalks
Newspapered the windscreen (something absorbent is best just in case)
Newspapered the engine and anything near by that could get over spray)

Left the bonnet just on the latch and used a small ladder/platform to give me good access

Cleaned the scuttle with old fashioned paint thinners and gave a wipe down with a soapy wet cloth and let it to dry.
Got some scouring pad and scuffed the surface a little to give it a bit of a key
Quick wipe with some tac cloth to get rid of dust and dirt.

Then a light spray over with the paint and let dry (it will dry pretty quick if its a light coat and warm weather
Gave it about 4 coats.

Let it dry harden for the rest of the day and then removed all the masking (I used a small craft knife along the sprayed edges just to break any sealing that may have happened)

Then the day after as it had hardened I gave it a little polish over for protection and it looks like new.

Makes quite a difference too that dull gray was always horrible and kinda let the car down!

I though about replacing it but removing all the seals and the trims on the a pillars just seemed like a lit of effort with massive potential to cause irritation later (you know there is always a slight rattle or vibration on a bit of trim that just doesnt go back quite the same way!)

Easy and cheap DIY job that leave you with some satisfaction at the end of the job that you saved a few quid that man can still a few things on his car without needing to call someone in!

It also save a job of having to go round with he peanut oil each time you wash it to make it look black again (i used to hate it in winter when you made it look nice an black with some silicon based product of similar only to have some rain run across it and make it streaky where some bits were still black and the grey started to show back through!

Teak oil has seen some good results for me, haven’t used it on my new ones but all old did well and worked on t5 too. Only a little bit is needed, it goes a long way.

Painting with textured plastic bumper paint works well.
I used Roberlo aircolor bumper. (tip: the distance you hold the spray can from the surface makes difference to the amount of texture) Pete
2008 L320 TDV8
2022 Hilux Rugged-X

I know this is an old thread, but for the sake of anyone using the search function in future:

I tried all sorts on mine (and other plastic trims over many years) and have found Infinity Wax Coat works a treat. I thought they were all the same, so had pretty much given up until someone recommended this to me.

There's a couple of reviews on YouTube, but this is the stuff:

https://www.infinitywax.com/products/plastic-coat