Picked up my gas tank today from a local radiator shop. It was treated with caustic soda only for mild surface rust. The tank looks great, but when I got it home I noticed that the inside of the tank is a bit 'sticky'. I called the shop to see if any neutralizing agents were used after the soda bath and was told no, and that it wasn't necessary. "Just fill the tank up and go". Not sure if I'm buying this. I know nothing about caustic soda baths (I only take showers ), but don't want anything I just want to make sure that there's nothing but gas going through the fuel system.

There is some slight surface rust returning on the outside of the tank so I plan to treat the outside with metal ready and then Por15. It will be a few days before I'm able to get the tank in the car and full of gas and there is already some VERY mild surface rust forming in the tank from sitting in the radiator shop overnight. Should I swish some metal ready around in the tank to convert what little rust there is and to protect from more rust forming until I can get it installed?
Do I need to neutralize the caustic soda stuff that it was dipped in? Do I need to stop asking so many questions?

If you were to neutralize the caustic (sodium hydroxide) it would be with an acid.

If you're really worried, swish vinegar (acetic acid) around inside the tank. Otherwise, just flush it with a lot of water.

When the caustic drys, it forms a white powder.

Oh, household use is a drain cleaner.

Well I feel a little stupid now, I just went out and looked at the tank again, and there isn't any 'stickiness' anymore. I guess whatever they flushed the tank out with has dried. However, lots of surface rust beginning to form inside the tank already (gotta love living in the northwest).

Metal ready inside to convert the newly forming rust and then rinse?

i just listened to your message robert. is the Metal Ready just a rust neutralizer? like Mar-hyde, Ospho? does the Metal Ready turn the rust black? my local radiator shop didn't even whan to discuss my tank. that flash rust is immediate alright. i seem to remember people having issues with the Por tank coat product.

k

Metal ready is a rust converter and a metal 'etcher' (to give por15 something to adhere to).

I just read this from the POR15 website:

Q: Must I wash off the metal ready after using it?
A: Yes. Otherwise a powdery residue will be left after the metal dries. This can be removed with a wet rag or by hosing it off. After washing off the treated metal ready surface, dry it with warm air (hair dryer) or with towls etc. Flash rust could appear if the surface isn't dried quickly.

Ack, sounds like I just prepped my tank for more rust as it sits waiting for me to install it this weekend :-/

Why not use WD=40 to coat the inside; when ready flush it and put in gas?

it's the coating after the everything else. as the fuel level goes down, air gets drawn in, there's moisture in the air, bare metal is exposed, and the rust cycle starts all over. almost like you need to metal ready, get it dry in a hurry, and coat it in short order. you'd have to spend the day at it.

Not a bad idea, but with the center divider inside it's going to be really tough to get all of the inside coated.

There's now rust on more areas than there was when I brought it in for treatment, though it's obviously not as thick. It's now in the house where there should be less humidity than in the garage.

I'm leaning towards running some metal ready through it to convert the surface rust and then rinsing thuroughly with hot water and then drying right before I'm ready to put it back in the car.

Had I known this would be such a PITA I probably would have left it as is and just replaced the inner sock-filter and called it good.

Radiator shop that I was going to go to said they coat them by default--yours didnt even have that as an option?

Nope. The original plan was for me to pick it up right after they were finished, instead it was finished after closing time, and left in the shop overnight. As they are a radiator shop (read: water) I assume that the humidity in their shop is fairly high which didn't help things.