I can vouch for this one Gaz as recently tried this on my 94 Velle that had Very Grey bumpers
I also found that you can make it go on easier and last longer by adding a little oil into the mix
The natural Oils in Peanut butter are fine but they often don't last so I put a little extra oil in an mixed well.
Olive Oil
New Engine Oil
New Transmission Fluid
3 in 1
All help choose whatever you have to hand
Just don't put the Peanut Butter back in the fridge
I just scoop a few spoon out into an old clean butter tub then add a little oil and mix well
Then just rub well in and buff off
Here are pics of my results.............
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