I agree with 1jaguar1. I would flush the brake system completely asap. look for a leaking piston seal on your calipers, that may likley be the fault. IMO even though we use synthetic motor oil (5-30) right?!! filter and oil should be changed at least every 6 mos regardless of mileage. Once the oil is introduced to the crankcase, the hydrocarbons other stuff start oxidizing the oil and cause it to break down regardless of heat (although that does it's share too). you may want to check into some solvents and add it to your immediate oil & filter change to removed sludge build up; take a long drive 1-2 hrs let things really heat up and then drain and use a good grade of synthetic oil and filter.
2001 XJ8; 18" one-off custom forged BOZE rims, 2.5" Dual Wicked Flow Custom exhaust and tips, K&N air filter. Coming soon: larger custom cold air induction, X-pipe and front resonator elimination, upgrade to all speakers.