The newer starters rely on a friction clutch... Reducing the friction makes the clutch more likely to start slipping... that is the failure mode when using Camguard with these newer starter clutches.
Except... there's nothing in Camguard to reduce friction. Here are their claims, from
www.aslcamguard.com/aviation No friction reduction, because they don't want starter adapters to slip.
CamGuard Aviation is a blend of high performance additives that fortify piston aircraft oils to provide the utmost in engine protection. Because of FAA regulations and costs, even the newest commercial aircraft oil technology is antiquated.
CamGuard Aviation addresses the complex interrelated problems of corrosion, deposits and wear in air-cooled piston aircraft engines.
CamGuard Aviation contains powerful multi-metal corrosion inhibitors that prevent rust and corrosion in infrequently used engines. Infrequent engine use can lead to rust pits forming on cam and lifter surfaces. This pitting can result in catastrophic spalling wear requiring a premature engine overhaul.
CamGuard Aviation contains advanced anti-wear additives to dramatically reduce the wear of cams, lifters, cylinders, rings, gears and valve guides.
CamGuard Aviation prevents scuffing wear from “dry starts” by maintaining an active lubricant film on critical parts, even after periods of prolonged inactivity.
CamGuard Aviation utilizes unique ashless deposit control additives that prevent the formation of varnish and carbon deposits throughout the engine.
CamGuard Aviation use in older engines allows component motions to free up sticky rings and valves, increasing compressions and reducing oil consumption.
CamGuard Aviation contains seal conditioners that nullify the effects of heat and time to keep seals supple, flexible, and performing like new.