They wouldn't stand behind it because it is almost certain that the oil did not cause the problem. Their products are among the best and although you may be convinced that the oil caused a problem it is just about impossible due to the consistancy of modern production. Many, many people have been convinced that the oil they used blew up their engine or caused some damage but in all the reading I have done through the years that has not proven to be the case even once, although fried cams and lifters due to oils with too little ZDDP appear to be on the rise. There was a rash of people in the late 80's who thought Mobil 1 blew up their engines or burned cams because it "clotted" with the leftover petroleum-based oil when they switched. What was the problem and why do you think the oil caused it?