DriVeRX87

Today I was driving my 16v and all of a sudden i start smelling burnt oil and then my oil level indicator turned on. I pulled over to check and hydraulic fluid was overflowing out the sls reservoir cap,also there was almost no oil in the engine. I tried to tighten the cap as best i could and put some oil in engine. I started it and let run for a few minutes and it was still leaking from the cap. I drove it home and the engine oil level was fine but the hydraulic fluid was still leaking from the cap. Does anyone know what the problem could be and is it super expensive to fix?