Oil in brake fluid


I have just been told by the dealer that someone put oil in my brake fluid. They said it was either done by accident or sabotage, yes those were the actual words used.

Because of this I will have to have everything replaced including brakes, brake module controller, hoses, master cylinder, front end calipers etc and the total cost will be $3600.00.

They are telling me that just replacing the master cylinder and flushing the system will not be a safe procedure.



Deb Miller



If there is in fact oil in the brake fluid and you have ABS, the dealer is absolutely correct about what needs to be replaced, I’m afraid. Have you had the car serviced at a quick-lube place recently? Has anyone else tried to add oil to the engine lately? Were you experiencing brake problems?


Find another mechanic FAST.

Were the brakes working before you took the car to them for service?? I can’t believe that everything needs to be replaced. Flushing out a system is NOT that difficult.

BTW…what make/model/year is this car.


If there is in fact oil in the brake fluid and you have ABS, the dealer is absolutely correct about what needs to be replaced, I’m afraid. Have you had the car serviced at a quick-lube place recently?

I do NOT understand WHY this can’t be flushed out. You can remove a caliper and open the bleeder valve and just drain it out.


From a liability point of view, the dealer is not going to recommend anything less than replacing the components. In practice maybe it can be flushed, an independent shop might be willing to try to flush the system (or at least flush the individual components).


Why did you take the car to the dealer?? Were you experiencing any brake problems?? How, exactly, did they determine that there was oil in the brake fluid?

Tell us more please…


The problem is that the rubber in the brake system can be damaged very quickly when it comes in contact with oil. As Craig pointed out, there is a big issue with liability. Maybe there is no damage (except for the master cylinder; its seals are almost undoubtedly damaged), but you’ll probably going to have a hard time finding a shop willing to take the risk. Flushing the contaminated fluid out by the regular bleeding procedure will push that fluid through the entire system. Who will the lawyers go after if a hose blows during a panic stop a month from now?

Again, what led you to the dealer in the first place? Are you experiencing any brake problems (you should be, if the master cylinder seals are ruined)?


I hate to say it, but I think they are right in that everything could need to be replaced. Every owner’s manual I’ve seen for a car that has ABS, all of them have big huge warnings about regular oil in the brake system and how it can completely wreck the brake system. I don’t know why or how, but they seem to be following along with those warnings.


Call your insurance agent if you have comprehensive insurance.


good call…an appraiser should be sent out to inspect this.


The brake pads and shoes would not be affected but if they are worn pretty good now is the time to change them, and since the shop would be changing calipers and wheel cylinders they should drop some labor since the pads/shoes must come off to access the calipers/cylinders.


Engine Oil I’ll assume or ATF?

I dunno… in an emergency years ago I had to put engine oil in the clutch reservoir. The one thing I noticed immediately was the clutch got very stiff and would release very slowely, I coudl lift my foot off and it woudl engage slowely.

Now have you detected any such change in your brakes?.

And how does he know it is engien oil or non brake fluid at least and how long is it suspected to have been in there.

Brake oil does not circulate very fast, so it woudl take a long time for oil to get from the reservoir to the cylinders.

Frankly, were it mine, I’d vacuum out all I could from the reservoir and flush it and see how it behaved.

By brake module controller, I assume the ABS Pump and not the ABS ECU, Ther shoudl be nothing wrong with the ECU part of it.


It can’t be flushed because oil rots rubber. ANY residual oil left in the entire system will eventually cause a seal to fail, and a loss of brakes.

This is not to mention the fact that evry rubber seal in the entire brake system is compromised already, regardless of how brief the contact with oil.