My daily driver, which varies as it is a company vehicle (usually a Tacoma or Tundra) takes about 1 1/2 to 2 months to hit 3,000. My wifes Rav4 takes about 3 months. Now, my 1993 Camry? About 5 years. The stuff I drain out in the spring to change could be rebottled as new. My 71 GS uses Amsoil that gets about 500-700 miles of use before being replaced yearly. I know, I know...