2013 Rx 350, 21K miles. This morning notice small amount of fluid on garage floor at the inside of the rear driver side tire. The fluid was like oil in feel and color, about 1/2 a teaspoonful on the floor and some on the tire. I use the parking/emergency brake often when parking in the sloped driveway, but not when parked in garage.

What is most likely cause of the fluid leak?

Thanks
Joe

 

it is probably Brake fluid. You could have a leaking brake caliper. It operates the rear disc brakes. The parking brake is mechanically operated by a cable (there are a pair of brake shoes inside the rear rotor). If you are able to get on the ground with a flashlight and look up at the inner tire, you may see more fluid or the source. One issue is such leaks get on the tire and coat the entire inner sidewall as you drive. Be sure to clean it off after it is repaired.

Open the hood and check the brake fluid level in the master cylinder. It is at the back of the engine bay on the driver side. There is a clear plastic container with fluid. You may have to remove a cover piece to see it clearly.

I think a leaking brake caliper would be under the warranty.

 

Could also be your rear shock leaking. These are known to have issues.

I doubt it's the brake fluid, but check anyway. You'd lost your brakes by now.

Another source of oil is the differential. The seal may not be holding the oil in and it is leaking through the bearings, making its way to the parking drum brakes, and then onto the tire.

 

Good points. That would be one serious shock leak!
One of my rear shocks has been leaking for a year and is just wet on the lower half. No performance issues but I may replace this summer as OEM rear shocks are under $40 each.

 

If it's brake-related, you'd expect to see a number of wet tracks radiating out - like a starburst - on the inside of the tire on the tire itself.

If not, look elsewhere.

 

Have your brakes been serviced? Brake fluid can leak in hose connecting bolt in caliber if not tighten properly or reused old gaskets.

The brakes never disappear totally as there are two chamber in fluid container as the fluid level keeps dropping. There's also sensor for low brake fluid level in master cylinder, you'll have it on in dash as brake warning light before loosing some brakes.
The warning light for low brake fluid level tends to be intermittent in the begin as you accelerate/decelerate and the fluid moves.

I think diff should not leak near/inside the wheel as the vehicle has independent rear suspension with separate driveshafts and not with solid rear axle?

 

Good point. This was from my experience with a 4Runner - solid rear axle indeed.