Cleaning steel: muc-off-like washes v Turtlewax?

[Brandane]

I believe washing-up liquid contains salt, which is why it should be avoided, even for cars, which, after all, don't matter much.

I suppose that depends on who has to take the hit on its resale value when it comes time to change the car. My car cost a lot more than my bikes, and apart from wanting it to look nice, I also don't want it rusting away!