[Synchro909]

I use the dishwasher tablets to remove any traces of grease before adding vinegar (50-50 with water). The vinegar can't work if there is a greasy film over the rust and dishwasher tablets don't foam up. I put the vinegar in before I do a longish drive, then leave it for a couple of weeks, maybe a month depending on how much crud is in tyhe system. I drive the car now and then while the vinegar is in there. When the time comes to drain and flush the vinegar, you'd be surprised at the junk that comes out. Refill with glycol and drive on.