My Jetta has 84k on it. 97 model year. Car sees track alot- abused honestly. I got the car at 79k. Now- the car was 2 owner owned, i was #3. I don't have maintanence info but here is my reasoining. 1st owner: traded at 40k with warranty intact. Second owner- had warranty till 70k. i got the car at 79k- oil appeared to be VERY dirty. 1 month after buying the car-Havoline w/fram was used. 2k miles later- Valvoline was used. the valvoline now has 3k something on it- and i am going to flush it out soon- with synthetic. Is it safe to switch over?