Quick math

Expansion bottle is about 10x10 cm, so each cm of change represents 100 cm^3 of volume

Total system volume is 7 liters or 7000 cm^3

so an inch of change is 250 ml or about 3% expansion of fluid volume.

From time to time I'll drop in here and mention that my coolant level is much steadier since I replaced the cap on my car. The rubber sealing washer broke in two pieces quite easily on the old one.

Carry on.

I have a 03 Toyota 4Runner V8. The header bottle when cold is almost completely empty at the MIN mark. I filled up to MAX and it leaked out when hot. Dealer told me not to fill up as system needs room to expand and that the level is normal.

Volvo P80's are the same.

Neil.

I'd say most importantly where is the level now ? Has it stabilized or is it continuing to vary up and down ?
If it's stable, then I wouldn't worry about it. Just keep an eye on it to see if it does it again. Mine doesn't move more than 1/2" or so hot to cold.

Heater core can be subtle source for loss without obvious leaks. Mine just smelled a bit, residue around the fins, and very slow reservoir leak. I drove it for a year, everywhere, like that. As has been suggested, it would be reasonable to take a relaxed approach for a bit. When the problem declares...

9492730 Intercooler is the only one I am unsure if. All other parts are the same. FCP fitment chart is good, Volvo parts web store is definitive If the intercooler works in both XC70 and T5 the LPT and HPT intercooler a are the same, sure looks that way here. https://www.volvopartswebstore.com/produ...

I could take the radiator core support of a parts 2000 in my driveway. It might not be crazy to ship , cost wise after the holidays.

Just as an aside, if your donor wagon is a vin 56 code, I would question the "R" designation; it won't matter for (most) of the parts you're after.

The screen handle is, in fact, derived from a drinking establishment ( one notch below Dive Bar status, RIP ) from that area; I used to work nearby, and the bartenders learned to tolerate us after we arrived from our duties much later than most Adults in Foggy Bottom. And they seemed to like the fac...

R or not, get those nice Perfo wheels from the blue donor. Good luck with the rehab. I hope the frame is still perfect.