Well, if you can get more service out of the equipment, go for it.

 

I'm glad the light bulb came on for you, as I wasn't going to mention it any more. I took a bit of flak for using it back when I did but desperation is a mother and necessity, the mother of invention. It certainly is unconventional, almost to the point of cheating. LOL
I did it eight years ago and am still driving today with no coolant loss. You tell me if that's permanent? Hell, if it blows tomorrow, I'd have gotten my money's worth (knock on wood). Even if it blew today, I can use it again. Understand that people even use this stuff for a final seal AFTER performing head gasket/head repair.

If coolant has entered the oil (milkshake) just change it with cheap oil and filter. Hell... if you have any used oil from oil changes, you can use that right now. You're experimenting if the engine can be saved! The stuff will start to work pretty quickly but driving 500 mi means it will push further into the head gasket perforation or even any cracks (cracked block). That's the beauty of it, you don't have to worry about the head being perfectly machined, etc. It can either fill the faulty HG or seep into cracked metal. There are people who have done the 20 min idle method and the fix lasts for a few months or years, then fails again because, I think it's just too light an application. It didn't work for me at all @20 min and I had to buy another bottle of KW and try again. Now please understand, if you've blown a hole in the HG as big as a barn door, the stuff will probably not work. In my case, the leak was very small.

Let me stress... read and familiarize yourself with how it works, so you can use it in wise manner. Read thru my threads. There are a few on this and they have links to each other. You have to drain the coolant and flush out all traces of it with water a few times before using the stuff. They say it's not necessary but preferably, you should remove the thermostat too (take a pic or note thermostat orientation), which is found where the bottom radiator hose attaches to the block. This is best done from up top, with the fan & shroud removed. DONT strip the two housing bolts there and if it's too hard, don't bother with that step.

If it gets freezing cold where you are, I'd probably go for a long drive and put the 400-500 mi on it immediately, unless you want to wait till the weather warms up. The stuff is mixed with water and you don't want it to freeze in the block. That doesn't mean you can't shut it off and let it sit. Just not let it sit too long or overnight, so the stuff freezes. If it's not freezing in your area, you can apply the miles with normal driving.

I took extra steps, like disconnecting the heater core and looping the metal lines coming from the engine with a hose. I was worried that it would block the core but I later came to understand that it would not. I also had the shroud removed and a glass bottle in place of the overflow tank. Each time the engine cooled, I'd pour the stuff from the glass bottle, back in. If your oil is mixing with coolant, I'd probably run a radiator flush prior to using the KW. This is to flush out the residual oil in cooling system, so it doesn't contaminate the stuff.

How it works:
The stuff keeps flowing as a liquid until it hits the high heat area of the head where combustion is occurring. As it enters the head gasket crack, the liquid pushes in & stagnates with the high heat... solidifies and turns to glass & melted copper. There is no other place in the engine hot enough to make it solidify like this. This is why it does not clog the heater core as the stuff keeps flowing at relatively cooler temps. However, if you don't disconnect the heater core, when you go to flush out the stuff, I would disconnect the two hoses and blow it out by mouth or with air hooked up, before letting the engine sit to dry. This is because I just don't know that the heater core drains along with the rest of the engine.

I wouldn't use Bars Leaks or any of that stuff you just pour into the coolant and leave in. I wouldn't even use the KW stuff that you leave in. Who knows what that does and blocks over time? You drain the KW back out! With that in mind, I'd jack up the rear end or put it on ramps so the engine is at an angle that drains real good. You can use tap water to flush and run the K&W and even when you flush again, but the very last flush, I'd use distilled water before final drain and of course, when you mix coolant to put back in, use distilled. Another extra step I took was partially blocking off the radiator with cardboard to the point of a slight overheat. The hotter the engine, the higher the pressure and heat as the KW is pushed into the crack and solidifies.

Good luck. I'm still tickled that I fixed mine for roughly 50 bucks and am still driving today, despite everyone telling me it wouldn't work. When I say I had nothing to lose, it's an understatement. I didn't have time or desire to perform all that work on a truck with low value anyway, so I would have let the truck go. It would have been a sin to do HG replacement and not replace all three chains, tensioner and a host of other stuff. I avoided all of that and the engine is running beautifully with high compression.

PS: This is not a KW commercial, LOL. I have no benefit or gain. It's just that I like thinking outside of the box and it worked this time.