I searched the forum for leaking type threads and ran across the rear differential issue and some shocks. I have just noticed what appears to be oil leaking just inside the driver side rear tire. My car sat for 5 days in my enclosed garage parking space. The puddle is about 6 inches in diameter. There are signs of smaller dried spots about and inch in diameter almost in the same area, so may be from earlier positions of the car. Any thoughts? I called dealer for service and he indicated they have not had issues with anything in that area. My car has about 20,500 miles. 2011 Supercharged.

 

Can you see what part of the undercarriage has oil on it? Might give some clues around where it's coming from

 

Might be brake fluid.

 

I placed some white paper towels under the area at lunch and looked after work. The fluid is actually a clear yellow color. The shock absorber appear to have oily dirt accumulation. Checked my brake fluid reservoir and it appears full. By the number of spots it appears this has been going on for a number of days or longer.

 

Photo

 

From your location description looks/sounds like a shock leak.

 

Brake reservoir fluid half way between max and min, could be brake fluid

 

Not unless the pads are new. Reservoir level is designed to remain between those marks for the life of a set of pads. Topping up this reservoir is not recommended.

Shock failure is common enough on these cars to be the prime suspect. Particularly if accompanied by knocking or creaking from that corner of the car. Factory shocks are built to cost not for longevity.

 

Pads are original to car, 20,500 or so miles. Interesting that reservoir is not topped out. Dealer is picking up car Wednesday. How much fluid would come from a shock leak? Dealer said if it was shock they would only replace that one, not rear pair? I would have thought they would be replaced in pairs.

 

The shocks are high pressure gas made by Bilstein and can leak a lot of fluid. Generally they only seep for quite a long time before they go soft. The gas chamber expands and compensates for some fluid loss.

High gas pressure shocks are either good or not good and can be replaced in single units unless the mileage on the other shock is quite high.

The shocks in my SAAB are original at 240,000 km and the front shocks in my Alfa are original at 230,000 km with no discernible loss of damping power.

Because the gas would force the fluid out if the seals were not perfect they last a long time unless they are damaged or defective from new.

 

I agree it is either the shock or brake fluid. The shop should be able to isolate very easily. It does not take a lot of fluid to expand into what you are showing on the towel and therefore would not show up in low fluid in the master cylinder or noise from a shock at this stage. You are doing the best thing which is get it repaired quickly before it leads to bigger problems.

 

If the reservoir was topped up now, it would overflow when the caliper pistons are retracted while fitting new brake pads.

Also- try not to open the reservoir unless flushing the fluid. Brake fluid is very hygroscopic and absorbs water from the air.

 

Thanks for all the feedback everyone. Will post once diagnosed by dealer.

 

Well, dealer picked up my car (no cost service to me) and dropped of the loaner. It was the rear, drivers side shock leaking as many suspected so they will replace. I also reported a rattling near visor and it was diagnosed as the dreaded broken sun roof clip. Probably hit a pothole that caused both issues. Thank you all for your input.