would I need to do the interior floor pans of my car? I'd like to do it so to protect against any more water coming in the car. A gallon would be waay to much. A pint maybe?

I'd get a six pack of the little cans. That way you have the best shot at keeping the unused stuff fresh. Every time you expose it to air it absorbs a bit of moisture. One of the little cans for each section of the floor will be more than enough. You don't need the fiber sheets right, you just want to coat it.

http://www.por15.com/prodinfo.asp?grp=SP&dept=1

It's way more than you'll need, but it's the best deal.

__________________
Chad
2013 Jeep Unlimited Rubicon
OBK#44
"Pleasure in the job puts perfection in the work." - Aristotle (384-322 B.C.)

SOLD
1985 300TD - Red Dragon
1986 300SDL - Coda
1991 - 300TE
1995 - E320
1985 300CD - Gladys
2006 Nissan Pathfinder LE
1998 Acura 3.0 CL

yea.. strip it of the tar and clean the surface rust off with a wire brush on my dremel and cover it up

$50 for the 6 cans seems good since I wont ruin one can

each can covers 12 square feet. That should be enough to do what I want to

If you've got surface rust, get some Metal Ready. It neutralizes the rust and leaves an etched zinc coating perfect for the POR paint.

http://www.por15.com/prodinfo.asp?grp=MR&dept=2

__________________
Chad
2013 Jeep Unlimited Rubicon
OBK#44
"Pleasure in the job puts perfection in the work." - Aristotle (384-322 B.C.)

SOLD
1985 300TD - Red Dragon
1986 300SDL - Coda
1991 - 300TE
1995 - E320
1985 300CD - Gladys
2006 Nissan Pathfinder LE
1998 Acura 3.0 CL

A 4oz can was enough to cover both rear and one front floor pan of my Amazon in additon to some other miscellaneous areas. They say 4oz covers 12sq ft, but it goes a farther if the area isn't rusty already. Since a w123 is a bit larger than my Amazon I would say 8oz should be plenty. You'll want some leftover to hit the battery tray too.
I prefer to get several little cans rather than one larger can and then work in sections. Sealing the can up again is annoying and only works a few times tops (be sure to use some plastic wrap between the lid and the can). I also store it in the fridge, but I'm single.
If you haven't used it before I'd recommend you buy one of their starter kits and start with the rear floor pans. It comes with plenty of Marine Clean and Metal Ready for a few cans of the paint. See how far that gets you and then maybe buy another can if you need it.
More than a few locals places carry por-15 around here, so if you run out and want to keep going you should be able to find more. Restoration and paint supply houses, tractor supply, marine supply etc.

__________________
1971 280 SEL
1981 Volvo 242Tic | 1980 Bertone Coupe

You can get their sample kit and then a few extra cans of the Por-15. I used up all the Por-15 they provided, but still have some of the Marine Clean and Metal Ready left.....

The sample kit is like $30

I used it on the bottom of my doors (weatherstripping channel) and a few little places on the inside of my doors.

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

id also like to add that 1 small can sure goes a long way. also, to keep the can fresh, wipe off the inner lip of the can w/ a rag with a little brake cleaner , place saran wrap over the top, and then close down the lid on the can. that way, the por15 does not bond with the lid and can