I only use vintage machines and only oil them when needed. I took my Viking 6430 and 301A into the shop last year. They were both cleaned inside and out. I just bought a Viking 6460 on eBay and it will go in for a cleaning in a couple of months because it only sews in reverse (common problem when it hasn't been used for an extended time period). I used my 301A for the first time since I had it cleaned (it stays in my van just in case I need it, or someone in my sewing group is having a problem with their machine. It has never failed to deliver.)