were the wheel wells' metal completely undercoated?

reason I ask, is I'm doing the annual underbody inspection/touch up , and it looks like some of the single layer undercoating is peeling reveling paint. So is this original factory undercoating that is flaking or something that was put on after factory?

 

Is it the waxy stuff or the actual tar based textured stuff? I'd just use an oil based product like fluid film in the winter.

 

https://www.rx7club.com/1st-gen-gene...ating-1145141/

 

There wasn't any factory (rust proofing) undercoating. It wasn't un common at that time to take your new car and have it done at one of several companies who specialized in it. Some dealers also added it as an up charge to the sticker price. I think the link above is in reference to the textured chip guard, which was factory applied under the paint to the rocker panels and lower portions of the body.

 

what is flaking off isn't the waxy stuff, and it isn't the brutish thuggish non uniform Rustoleum tar undercoating. It is uniform and thin and black that is peeling off showing the sunrise red paint. Some paper receipts in the car suggest the car started life out in Las Vegas.

The link up above is for outside the wheel well. My question is about inside, and about the underbody. How could you use a squeegee in a wheel well, or the irregular underbody or undercarriage.

It was 72 F today with low humidity, and the heat kicked my ***!! At 65 years old, I'm such a candy *** ! When I was 20, I could work 12 hours a day in a shipyard in +90F and humid as hell southern Louisiana.

 

Mazda used the same stuff all over the bottom, and then painted the car. there shouldn't be anything else on there.

 

So that is Mazda OEM black stuff that is flaking off. Solves that mystery.

I used up 2 partial cans of rustoleum undercarriage undercoat left over from last year(s). Maybe there was 5 by 5 inch area in total that needed touch up. Should be good for another 37 years

 

Fluid Film and other lanolin based undercoatings seem to be the best (for now).
But my car has survived 40 years now with those tar based undercoatings.
Should I stick with them?
Should I spray the insides of the frame rails with Fluid Film?
Should I spray FLUID Film over the old tar based undercoat?