I have seven collector cars. due to time restraints, I put on no more than 100 miles per year on each car. ( I know I should drive them more often) the cars are stored from late October and started up in early may. (Wisconsin) cars are never started up during storage period. I use Valvoline .vr1 racing oil 20/50. my question - how often do I need to change the oil in these cars. at $6.00 per quart + oil filters, I am probably throwing money out the window by changing oil once a year. when I drain the oil, it comes out looking like honey. can I get by with changing oil every 2-3 years or more? please advise. thanks in advance, jim