What coolants did you add when refilling the reservoir?>Water Only
OK, you evidently know about the HOAT coolant incompatibility with others, thats good.
Make sure you use the specified coolant...
Did you at any time notice fluid on the driver side of the coolant reservoir?>Not that I've noticed, just for clarification: are you referring to the section of the reservoir that is not as deep as the rest?
It's the shallower section on the right as you look in the engine bay
Is the oil level higher than it was? Notably lower than it was?>After having the vehicle towed back to my house I checked the oil level, and yes, it is extremely high, well past the gauge.
This means the head gasket is blown right?
Probably, yes, although it could be a cracked block or cracked head, but something bad is happening/has happened. It is likely that when you drain the oil that there will be significant water in the pan. That is a definitive sign that things have gone badly awry.
Have you had any service done to the vehicle within the last 6 months? If so, what?>I changed the oil and filter, and replaced the fuel filter about 5,000 miles ago.
OK.
When you fill the reservoir, where does the fluid leak out? If it empties within 5 hours thats a notable leak.....>Until yesterday I hadn't noticed the fluid leaking out, I refilled the reservoir today and still haven't noticed leaking yet. But I also haven't been able to get the engine to turn over.
DO NOT TRY TO CRANK THE ENGINE AT THIS POINT.
I recommend that you-
-Drain the coolant completely, including draining the lower hose;
-Drain the oil and fill it with fresh new lube oil to reduce corrosion;
-DIsconnect the battery so nobody tries to crank it.
-If it were me, I'd try to get some protectant into the cylinders to prevent rust, either by removing the glow plugs or the injectors and squirting PB blaster in.
When idling and filling the reservoir, did you notice any exhaust smell from the tank? bubbling?>No.
OK.
When you stop to fill the reservoir, was there pressure on the tank? Any oil visible in the coolant?>There has been pressure on the tank every time I've opened the reservoir with the engine hot. There has been no oil visible in the coolant.
OK.
Off topic- Have you changed the timing belt yet?I have not had the timing belt changed.
Well, now is your chance!
If you are capable of and interested in investigating on your own, I would plan on an overhaul with gasket change in the near future.
If you don't want to tackle it yourself, find a GOOD diesel mechanic and make sure he knows about the quirks of this engine. Holler if you want advise!