I had a heck of a time trying to get all the orange out to replace it with new gold type. I think I need to do it s second time as there must be some orange left in there mixed in. Any advice for my second attempt?
I do this only during warm weather with no freezing temperatures. I drain the coolant from the low point, refilling with distilled water. I run it until warmed up, thermostat open, let it cool and repeat. Depending upon how patient I am I might do this 7-8 times over the course of a few days, distilled water about $1.00 gallon. I don't know if there is an easy way to drain the block on your year. I am unwilling to try to remove freeze plugs, etc. Also the older models have an iron block, not sure of yours, so do not allow distilled water to remain in more than a few days or I have found it starts to get an orange tint, corrosion. When what you are draining is pretty clear add your new coolant. Adding new coolant is a little tricky, my coolant capacity is stated as 12 quarts, judging from how much distilled water I have to add think about 7 quarts drains out, so I think there is about 5-6 quarts of distilled water left. I add full strength and keep measuring with an antifreeze tester. Adapt as needed for your year. Maybe there is a better way for yours.
I did the same thing when I changed over my coolant ('17) as stated above, except mine would only drain exactly one gallon at a time. I did a total of 5 flushes using distilled water until the color of the last flush was almost clear. It still had a slight tinge to it. I added one gallon of the new stuff since at this point I believe all I had was water, that would give me some protection (about 30/70 was my guess). Living in Texas I believe that would be sufficient for a while. About a year later, I drained one gallon and added another straight anti-freeze.
Yeah, it sucks. The above method is really the only way as a DIY. Shops have an airlift to forcibly remove all the offending coolant. On my Mustang I just flushed it twice and said good enough, the color is an off orange still but orange and yellow can safely be mixed with no issues, so I'm not worried about it. I also didn't want to worry about mixture dilution, since it's very difficult to gauge how much distilled you still have left in the block. Don't want her freezing while it sits over winter.