Engine flush has been available since the 50's (and probably before that) specifically for the deed so why use vinegar?
Do you think you're out-smarting the system? You can more or less depend on a tried and proven product and I belive it's not expensive.
But as Pgitug points out vinegar has many uses. We use apple cider vinegar (and two other things) to get rid of black mould on the cap rail. Chris has a formula that includes ACV. Don't know of a commercial product that works as well. When the commercial products failed I mixed our own oil finish for the cap rails in Alaska. It worked ... ok. Got us by in the very wet weather.
North Western Washington State USA