Valve seals may or not help. Unlike mercedes gas engines of old they do not seem to be as critical.

Some have reported improvement as well. So in general it is a crap shoot in my opinion. The good is that it is a cheap one.

Also have your friend try running with the oil level about halfway between the marks on the dipstick. Some like to consume more oil when they are filled to the top mark. Make sure the correct color code dipstick is present as well.

Is there any indication of waste vegatable oil usage on that car?