Just to the nitty-gritty down and dirty, I normally add/top off the coolant resevoir with PEAK 50/50 (the bottle that has a yellow cap and says for ALL makes and add to ANY color coolant). Well, today I was at wally world and got another bottle of PEAK 50/50. Then when I got home I noticed that this new bottle has a red cap and contains some sodium something and organic inhibitors, otherwise it appears it is the same as the yellow-capped bottle I already have. I remember reading somewhere here about all-metal radiators (which I have) and how some coolants eat away the solder joints. Organic inhibitors the cause? I don't remember. When these coolant manufacturers say for all makes and models, do they mean mainly newer cars or do they include older cars?

Ah, I just want to double check with this PEAK with a red cap I bought.