What caused this

Ah, I see.... 'regular'. I just did not want people to think there were not 'readily' available oils that have adequate ZDDP. 'readily' means it can be gotten without too much effort.... uh oh, I guess I need to define 'too much'.... LOL

Now you have me thinking to look and see what one COULD get off the shelf that has adequate ZDDP levels. Research for another day.....