The other thing that people must understand is what a shop actually is. Your local quick lube is not a repair shop and any advice they give should be taken in the same manner as advice from this forum. For the most part certified automotive technicians do not work at quick lube's ... and even though you may see an ASE patch on their arm, this doesn't mean they have mechanical training or experience to properly diagnose your automotive problems.
There are levels for each type of automotive related work that are eligible for ASE certification. HERE
are the current ASE certification levels. Anyone (generally) working a quick lube would fall under the A Series, which is basically general automotive knowledge and basically about what the average auto-enthusiast would know.
This means you should pay careful attention to how the QL tech words things. If they say 'your transmission is slipping and needs a flush
', you should understand this to mean 'I think your transmission is slipping and may need work'
. It is the tech's mistake in saying he is positive in what is wrong and needs repair. He does not have any certification oversight backing his opinions and should not be trying to work beyond what his is certified for, that is unless he is receiving a second opinion from someone who is.
Now besides the ASE certifications there are also manufacture specific certifications. The reason for this is MFG.'s have information that is unique only to them, such as the programming in a vehicles computer. As an example, For uses what is known as Standard Corporate Protocol (SCP). This is a 'trade secret' and covers all the inner workings of the computer. The Government specifies certain emissions related things be universal between all MFG.'s. Everything else is unregulated. Things like computer controlled shock absorbers and not regulated and are MFG specific.
This means that a Ford certification will be more specific and a tech that has this level of certification will know more about the inner workings of the Ford automobile. With how complicated the newer vehicles are becoming it is a good idea to heed the advice of a Ford certified tech vs that of just the ASE one. Though the ASE tech may be able to diagnose the problem the same, they may not understand why the problem occurs whereas a Ford tech may.
But, one advantage of working a general non-make specif shop has is, they may see similar problems from various MFG.'s and may have a simple and reliable fix based on previous experience. This can be helpful at times. But if the repair does cause a problem down the road and you go to a make specific shop, the shop may blame the now problem on the 'quick fix' of the general shop and repair it with the correct part. So it comes to be that just as with your personal health and having a family doctor, having a family mechanic is a good thing. If the same shop works on your car they will have record and know what was previously repaired and if the now problem is under the warranty period of the replaced part they will let you know.
What it basically boils down to, IMO, is that with newer vehicles having repairs done at make specific/dealer service centers is the best practice. They employ the correct diagnosis equipment, certified employees and use the correct repair parts to keep the automobile running as it's intended to.