New to me 01 Tahoe coolant issue

[69C-10SWB]

I have a 01 Tahoe w/5.3 with 142,000 mi. Got it 7 months ago. Runs good, no overheating. First full-size SUV for me and love it so far.
A few months ago it started loosing coolant, no visible leaks, low in overflow tank. Recently started to have to add coolant more frequently. I drained radiator and overflow, refilled with prestone (mixes with all colors makes etc.) and distilled water. Old coolant was orange(dex-cool I guess) and not at all dirty. I added a bottle of Bars Leak radiator heavy duty stop leak. Seems to have worked, haven't had to add any coolant, still runs below 210 on temp gauge. Anyone with a similar experience? Any thoughts on Bars Leak?