<VV> oil question

[Ken Clark]

What is the opinion of some of you oil experts on this oil I found in an Orscheln Farm and home supply store.  The oil is called "Country Tuff" and has the designation "SL" which I under stood to mean it has the ZDDP ingredient we want for our Corvair engines.  I've already put the Mobil 1 in one car and wondered if I might be asking for trouble if I were to use this oil in one of the other ones???  
Ken Clark of Sunny and Springtime in Indiana