Interpret my spark plugs

Engine: Lycoming O-235-C1 (low compression)
TSMO: 270 hours
Hours on plugs: 130
Fuel; Half time on 100 LL / half time on autogas
Oil: Aeroshell 100 Plus
Additive: Camguard
All plugs quite similar in appearance. Some slight carbon buildup up on #3 and #4 bottom. The rest have a coating of whitish/yellowish crusty material. All cleaned off easily with a small portable spark plug cleaner.

This service was part of conditional inspection.

Engine seemed to run fine. Never a problem with the engine and high temps.

I'm wondering what the white/yellowish crusty stuff indicates?

https://photos.app.goo.gl/kNGegsyMTtFbaE2k8

https://photos.app.goo.gl/xFmKQKZL9fswH9Ua9

TIA
Gary

Normal deposits from TEL and Bromine scavenging.

More important, make sure you gap them ( 0.016" - 0.018") and check their resistance, and they should be under 5000 ohms.

They may well be near end of life.