We just performed a patch test to some oil samples. We are performing this test because we are having premature wear in our con-rod and main bearings. Our SOS sample analysis does not show abnormal contamination. Please, could you see the attached picture and give us your opinion of what kind of contamination is it? Also do you know where we could find information to interpretate results

90X_-_1.jpg (120 Kb, 115 downloads) Particles at 90X

It is very difficult to interpret what is on your patch from this photo as the resolution and contrast are not very good. It looks to me like flakes of either paint or gasket material. The wear particle is fairly small and only one visible which is good.

Yarango,
I agree with Buckhntr re the resolution however from what I can see it looks a bit like bearing babbit material. However it might be leftover material from previous failures etc. Check to see if the material is magnetic. If not then it might be bearing material.
I have never come across a good technical reference to assist in the understanding of filter patch testing. However there have been several articles in Practicing Oil Analysis magazine etc to provide some insight. You might want to consider getting a copy of the analytical ferrography atlas. Some of the pictures in there can also help give you some guidance.

regards......