hello, i drive a 2000 v70 xc awd. i have issues with warning lights on my dashboard. the ABS light and traction control lights turn on simultaniously every now and then. i shut the car off and the lights are not on when i restart the car. then at some point during the drive, the lights will either turn on or not, it doesnt seem to occur due to different road conditions or really anything specific. this began i believe shortly after i changed the brake pads 2 weeks ago. i also have a check engine light, and a service engine light that are frequently, but not always on. oil looks good(just changed about 500 miles ago) and engine runs fine. any ideas? the car has 135,000 miles on it. i have heard both good things and bad things about synthetic oil. should i be using synthetic? thanks for the support