Ultrasonic cleaning is very effective and safe for all types of film.
Filmguard does nothing to offset vinegar syndrome, it quite possibly makes it worse, not allowing the film to breathe. Filmguard is great for prints in good condition, it makes them run more quietly and smoothly through a projector, and minimises the risk of further scratching or damage during projection.
Here is an example of an ultrasonic film cleaner in action.