I can't really be sure about that. As I said, it's been 2 years since, and my car is mostly parked in the sun. And with that 2.4 liter engine speeds like 120-130 are easy even within the city, and so far so good.
I've had previous experience with them and normally if I ask them to do some job which they think is not the right thing to do, they just refuse it. That's why I plunged into it, and while they only claimed a little improvement, I was actually surprised to see a major improvement.