I'm looking for a Ford Ranger and I found a 2000 with low miles and very little rust (near impossible to find for this age in New England). Everything looked great on the engine, it has a minor oil leak somewhere (looks like the valve cover?) When I opened the radiator cap I noticed some gunk on it and it had an orange/reddish color which was odd because I was pretty pretty sure Ford uses green or yellow. He's owned the car for 8 months and put a few thousand miles on it. I took it for a 10 minute drive and it got up to temp and didn't start to overheat at all so it doesn't seem like it's having the typical overheating issues. I left to go look at another truck and the first guy sent me a picture of the other stuff he's giving me with the truck and in the picture there's a bottle of Prestone Dex Cool so I'm almost positive he's the one that added it. I haven't called him back yet and I have a few questions before I call him back. There's a lemon law in Massachusetts where I'm buying it so if it's a massive problem I can return it to him for a full refund. 1. How much/what kind of damage can 8 months of dex-cool mixed with green do to the system? I didn't see any coolant leaks anywhere and it doesn't look like there was any K-Seal or any sort of leak stop used. 2. Would it be any different if he flushed the system at the radiator before adding the dex cool rather than just topping off with green? I doubt if he flushed he flushed at the block I'll ask after I call 3. If I do a complete flush of the system from the block, radiator, and water pump and refill with distilled and Ford green, will I be able to mitigate the damage? Thanks for the help.