I acquired a 1996 855 Turbo that was off lease with 44k on it two years ago. Not leaking, switched to Mobil 1 10w30 (Nebraska) year round and have had leaking accumulator, brakes, tranny, windows, and rear main seal. I do not blame any of that on the oil, just on service the car lacked in first life. This car has no "flame trap" and everything has fallen under Volvo Certified warranty (except A/C) and that was just poor design. (Splash shield under front bumper was off the car allowing sand/salt to accumulate on top of rim of retainer band on accumulator causing -rust). Rear main seal failed after 5 hour blast from Tulsa to Omaha in sub-zero temps. I will not use anything but Mobil 1 in this machine, it has cleared all the dino residue in just 8,000 miles and improved mileage by 2.7 mph.