I've used Por-15 on my Z and it seems to work just fine in stopping rust. Search throught the archives for more info. You can buy it in a 6-pack of 4oz. cans which I would recommend. Once you open a can and reseal it, you may have a hard time getting the lid off again if any of this paint gets around the top. It will set up rock hard. I was able to do my left front wheel well and it only took just over 2 ounces of a small can. I've read where some people have even used it on the control arms and other suspension components as well since it sets up so hard and leaves a nice finish. POR-15 recommends that you top coat if the area you paint will be exposed to sunlight since the sunlight will cause the color of the paint to change. Overall, I would recommend it. I plan on using it on the entire undercarriage of my Z as well as on the interior to protect from rust.
Later,
Mike
Later,
Mike