Just came back from dealer today. My story.
At 40k miles, dealer advisor told me about the tensioner leak with my '16 Mazda6.
I refused to change it on the spot.
Got home, I did see thick oil stain on the tensioner as the OP showed.
I wiped it clean and have been keeping an eye on it.
Fast forward to yesterday (at 47K miles, 6 months later).
My Mazda6 exhibits a ka-ka-ka-ka noise when I accelerate mildly offline or when cruising trying to pick up speed. i.e. engine revs up under load. No such noise when engine was at constant RPM.
I recalled the tensioner leakage 6 months earlier. So, I visually checked it again. I did see new oil leak. At idle (again, constant RPM, there was not abnormal noise.
It showed up with power braking if you know how to do it... (i.e. one foot on brake firmly, another on gas pedal .. be careful while doing this)
I visited the dealership today. I reproduced the noise with the advisor riding shotgun.
He heard it too.
I mentioned to him that could be the tensioner. He was not sure about it.
I decided on replacing the tensioner and the belt to see if that fixes the problem.
Two hours later. Good news.
It did get fixed.
A few hundred bucks lighter in my wallet.
Anyway,
PE03-15-980C was the part they used.
As to cost, it is expensive in bay area... so, not a good reference to you all.
Lesson learned.
Better replace it when it leaks.
It is on borrowed time.
I checked the tensioners on my '14 Mazda3 and '17 CX5.
Did not see any leakage.... yet. Knock on wood.
BTW, while I was there.
I checked out all the new vehicles (very very few in the lot).
Everyone of them has ADM of $4995 on the window sticker.
Man, crazy time.
