Gaseous.
It's not an attitude towards clients at all, I think that is quite an unfair thing to say. It was more a statement that goes all with what you were saying about things that engineers and maintenance companies do that annoy pilots. It is very much a 2 way street and sometmes both sides maybe need to communicate better. Parts on your machine that need changing and are high cost should of course be notified to the owner operator. I would not go ahead and do high cost work with out notifying the client and receiving their ok before going ahead, generally in writing (the joy of e-mail). As Hatters stated, the decision to replace the item is that of the engineer, not the owner or pilot, as he also stated you are within your rights for a second opinion.
Maintenance costs are a constant bone of contention between operators and maintainers, a reason why one of my former employers decided to set up his own 145 organisaton, a very costly exercise but one I know he is very glad he did. Generally we engineers don't change things for fun, we do it because it needs doing to ensure your continued safety, a matter we all take extremely seriously and you are right to say that you consider the engineer who used to work on your aircraft a friend, that is how the relatonship should be between 2 profession people with a high level of mutual respect.