Questions re: My first Falcon!

[Judgie]

I purchased my 2000 AU I XLS Cab Chassis ute in late April of this year, after having owned a 2000 Holden VS SIII V6 ute (and coming from a Holden family, though my old man's father was a Ford man ).

Decided to get a Ford as something different, after (funnily enough) an electrician in an FG XR8 ute failed to give way (didn't even look) and pulled out in front of me from a side road (I was on the main, it's a 90km/hr zone....). We all got incredibly lucky re: flesh and blood, he got lucky with his vehicle (minor front right quarter panel damage), and my VS took the brunt, Whole front right of my vehicle pushed back to the firewall, it crumpled perfectly as designed to be honest, a good thing since the VS base utes don't have an airbag, this base Falcon ute does!! . No neck spinal fractures for me thank god!

Anyway, I got lucky and picked up my AU, one-owner, with logbook, ALL receipts (not joking) and service history (the guy was fastidious with servicing, I'll be back to buy his BF XR8 ute in several years time ), with only 55,000 kilometers on the clock. He bought it for a new business he was starting, but that deal fell through and his missus ended up driving it, about 50 kays each way to work and back, 5 days a week.

So i've had no issues until now (now have 61,000km's on the clock), though being such a low kay car, it's obviously had long stretches of garaging, and i've expected a few bugs to arise... sooooo..............

It's lost a liter of coolant in a little over a month

So I've done a lot of research on here an elsewhere, and in the meantime replaced the coolant reservoir cap as first port of call, and will be doing a TEEKAY c02 test on the coolant tommorow.

Questions:

(1) I understand the head gasket issues were mostly eliminated with the AU series onwards through the use of a steel head gasket? could this be the issue here? there's no oil in the coolant in the reservoir, no milkiness in the oil in the sump, and no apparent external leaks. No steam from the exhaust except when cold, and held a piece of A4 paper an inch from the exhaust for a minute with engine at operating temp, no moisture trapped except what would be expected from the combustion of gasoline with oxygen. It's had a compression test, but NOT a cylinder leakdown test. Will have to have that AND another cooling system pressure test done.....

(2) Everything appeared and appears to be in sound mechanical condition, and NO rust (surface, deep rust, or paint bubbling) that I could find anywhere on the body or underneath. She might need a new exhaust, but after ten years, i'd be expecting that. I was over and under the ute for an hour, and had it checked out as well. Idles a TINY bit rough, but a huge improvement over the 3.8 liter Buick V6 in smoothness and refinement .

What else might I expect with this vehicle????, being of quite low kay's and in quite sound condition according to sound, sight and smell???.

I hope to god the surge tank cap perishing was the cause of coolant loss........