I use Evapo-Rust and love it. It has done a great job on the inside of my gas tanks.
It is safe on many paints... BUT:
I have noticed it will completely remove the black paint frame paint on my CT3. This has actually been a great help as it removed all the paint from my skid paint as well as the rust, which made it easy to prep for painting.
If you need to easily strip and de-rust a black painted part on one of these bikes, I recommend soaking it in a bucket of Evapo-Rust overnight.

Thats good to know it removes frame paint. I love evaporust. Just soaked a pair of 30 year old tin snips in it 2 days ago overnight and literally every bit of rust gone and it will wick into small spaces like threaded screws. With modern paint seems like it won't effect the color or remove paint. I saw a test on a bicycle forum you tube and he tried many derusters including acid and evap was the only one not to change the color or damage the paint. Evap can be reused just pour back into bottle. I pour it back accept the sediment that collects at the very bottom of my soaking container.

Took your advice. Works great. Sure wish I'd known about this stuff years ago. Thanks for the info.

I have a question about what to do after using the evapo-rust. For on smaller parts, like bolts, do I need to coat them with anything to avoid re-rusting? Same with the inside of the fuel tank? The chain?

If I won't be putting fuel in the tank right away (still fixing everything up as parts come in) should I avoid using the evapo-rust until I'm ready to start it up?

"If I won't be putting fuel in the tank right away (still fixing everything up as parts come in) should I avoid using the evapo-rust until I'm ready to start it up?"

Not a bad idea, but I usually spray some WD-40 inside, and then rinse it with a tad bit gas when I'm ready to fill it. Other guys fill it with premix.

I have 5 bikes in the corner of my barn and that won't be getting any attention for a long time yet. I have drained the old gas and topped off the gas tanks with used motor oil. When I finally do get at them, I will dispose of the oil and swish it clean as needed.

Dang Schu, i would have to drain my DuraMax a bunch to accumulate enough oil to fill my bike tanks.
Can you still get re-refined oil. My Dad put that in his clunker cars.

Let me clarify. I only do this to bikes that are waiting to be restored. I don't do this to running bikes that have simply been in storage. Yes you can still get re-refined oil. We use it in automatic chain oilers on conveyors we build at work.