Question about Brake Rotors



I recently had my Subaru dealership check out a problem with a tire (long story, but it was a simple fix). They did a general check and said my brakes are at the lowest level for safety and need to be replaced. I already knew that and will get it done. They also said the rotors are rusty and need to be replaced.

I thought rotors get rusty right away, after a rain, wet streets, carwash, etc… I’ll have my private mechanic check it out–very trustworthy guy-- but just thought I’d get other opinions on here first.

BTW-- the dealership also suggested all the “flushes” which you guys have taught me are a scam. Thanks for that!

99 Subaru Legacy sedan, 140K


‘rusty’ is almost never a reason to replace rotors, but these days many are pretty thin (can’t be turned), so you may well end up replacing them with the brake job.


There are three main considerations that should be taken into account when assessing brake rotors; remaining thickness, lateral runout and surface finish.

Often these days, the rotors are nearly at the minimum thickness when new because manfrs want to reduce unsprung weight as a means to maximize fuel economy. So, by the time the pads are worn out, so are the rotors.

On some cars, the rotors are very inexpensive due to design or by the sheer volume of their installed base. In that case, the labor to inspect and potentially recondition the rotors does not make good economic sense. This is rarely the case when doing this work at a dealer due to the typical higher expense of their labor and parts. The advantage of the dealer is that they will use the same OEM parts that went into the car in the first place and so the likelyhood of squeals, squeaks and other issues may be far less prevalent than a “muffler shop”.

The fact they made this assessment from a visual inspection says one of three things to me; A. the surface condition is so poor that it is obvious they should be replaced or 2. they don’t like callbacks (you’re disappointed and return for a subsequent fix) so they want to just replace everything as insurance against issues or III. they’re just looking to maximize the repair expense.


As long as the rotors are true then rust will not be enough reason to replace them. I’m glad that you have learned that “flushes” are a bad thing. Thanks for your feedback!


Rust is not necessarily a reason to replace rotors and certainly not if they’re referring to rust on the center flange or outer rim.

As to flushes being a scam, that is a blanket indictment that is not true. At some point in time a flush of certain things is not only recommended, but beneficial.
At 12 years of age and 140k miles it’s entirely possible that certain things needed to be flushed years ago if it has not been done.

Look at the owners manual and see what it says about coolant, brake fluid, etc.

  1. What the others said about the rust.

  2. We have a '99 Outback wagon with 287k miles and just had the original rotors turned within specs. Taking into account that my “better” half drives this car and she is MURDER on brakes, your '99 with a mere 140k doesn’t likely need new rotors. But you never know, so trust your trustworthy mechanic, not the dealer.


Thank you everyone.Your comments were all so helpful.

I really appreciate the last comment about the 99 Outback with high mileage. I’m pretty easy on brakes and have hopes that turning the rotors is all they need. It also helps to know my Subaru can last much longer with good maintenance!


If there is a ridge of rust on the edge of the rotors and it is thick, I recommend replacement too. I wouldn’t even bother measuring them. If you can see through the ventilation holes in the wheel and the shiny part of the rotor doesn’t cover just about all the rotor surface, you are not getting full contact of the brake pads.


Thank you!


If they are going to turn and machine your rotors ask for cost vs simply replacing them. Rotors are typically inexpensive in comparison to hourly labor rate(turning/truing) rotors.

Putting new pads on rusty rotors can lead to a complaining customer returning to shop with noisy brakes.


Will do-- thank you.


Ask your dealer and I suggest that you use these exact words: Have the swept areas on the rotors where the pads touch been reduced in area from original due to rust?

If he says no, then ask where the rust is and why is it a problem?


Excellent advice-- makes it very clear and direct. Thank you.