Anyone know the best product to clean black plastic hatches that look like they have a bit of oxidation on the sides, specifically on a old Formula? Any help appreciated. mike

Clear plastic or solid plastic? Pics?

I believe the tops are clear/plexi which are fine, the sides are hard...

I've used both Meguiars #17 Clear Plastic Cleaner with pretty good success on those types of plastics. Commonly the gauge surround on older boats is made of a similar material and it helps pull a lot of dirt and grime out of the plastic as well as darken the material. You can also try to give them a little polish with Meguiars #10 Clear Plastic Polish also which may give you the finish you're after. As crazy as it sounds you can also protect this finish and maybe slightly darken it further by using Collonite 845. Wipe it on and then wipe it right off. These types of plastics are commonly damaged by washing with something that isn't PH neutral which will lead to streaking and drips in the plastic. Sorry for the long winded post.

Thanks VCMike, will try.