I would like to know if Synthetic oil or the Regular oil is really worth the difference in money 5$ veres $1.30 I talking any real trials and proof. I have 1 1999 truck Z71 and 1 2002 Buick car and 1 1993 van G20) Would like to use the same oil in all but no problem to use a different, I change oil every 5000 along with the filter. I drive each around 12,000 miles each a year except for the Van around 5000 miles I am retired and don't have a large income, we are talking $650 veress $175 for 3 auto oil change and filter in a year. which is a difference of $475 which could be a severial night out for dinner, or month worth of food. and would like to drive each of these Auto a least 150,000 miles each. If you have real info on this all would be appreciated. My best friend which is holds a deg. in Diesel Mec. Says Reg. and change every 3000 miles. Would like other opi.