Havent used either. Need something for the trim
Thoughts - Comments

 

I love BlackWow. A little bit goes a long way and it outlasts anything I've used on the plastics outside the vehicle yet. I've never used 40 but have heard good things about it.

 

Do you know if either one 'runs' when it rains?

 

I didn't experience any running with BlackWow. The key is to apply it right. A little bit goes a long way. If you use too much it will run. It also looks like hell if you get it on your paint so for tough areas like door handles you should tape around them with blue painters tape. If you do get it on the paint just get it off in a reasonable amount of time and don't let it sit any longer than you have to.

 

Black Wow is great stuff. Best product I have ever used for trim. No running at all. Just as esf said, use sparingly. Never tried Megs 40.

 

#40 is a water-based dressing and it will streak to a certain degree in the rain. I've been using it for years and years now... It's a VERY solid dressing but, the two products really aren't all that much alike, IMO (yeah, I use BW too).

I personally like Vinylex over #40.