Can someone shed some light on oil? I have 2 old tractors, one I have had for a while and the other one I just acquired. I know not to use detergent oil in these old tractors but other than buying oil on-line or having a store order it for me I am having a hard time finding non-detergent oil locally on the shelf (plus the cost is high). I have had stores try to sell me non-detergent lubricating oil saying it is the same as non-detergent motor oil. Even when I look it up on the internet, people advertise it as motor oil but the label on the bottle says lubricating oil. Both are SAE 30, but the bottle that says "lubricating oil" also says ISO 100. I know what the numbers mean I just don't what the difference is. I can't believe it is the same or that it is interchangeable but I can't find out what makes them different.