1. Mack T12 Piston Distress October 11, 2005

2. CMIR 55723 piston 4 CMIR 56010 piston 5 TRWL = 101mg TRWL = 31 mg

3. Concerns about “Blistering” Noticed to large degree at Afton on two matrix tests with high ring wear (~100 mgs) Noticed to smaller degree at Afton on matrix tests with “normal” ring wear Has been seen in some degree at all test labs “Blistering” seems to be normal, its just a matter of degree?

4. Does “Blistering” impact TRWL It’s a reasonable assumption Degree of “blistering” per cylinder within a test doesn’t appear to correlate with ring wear in same cylinder With EGR rates of 30% & 15%, “blistered” material would be ingested via EGR into cylinders as intake debris

5. Possible Blistering Impacts w/New Rings -excluding the high Afton results With 2 of 3 matrix oils, there’s a nominal 2-1 spread within lab on same oil (~30 mgs to ~60 mgs)  would the results of 60 mgs been lower w/o blistering or higher with more blistering-possibly?

6. Thoughts This “blistering” is presumably caused by heat distress High cylinder pressure, high intake manifold temperature/pressure, high fuel rates, high EGR rates and advanced timing could all be contributors How can we separate corrosive wear from abrasive wear?

7. Path Forward Examine all operational data Examine pistons from all labs Look for any and all contributing factors  tightening of control limits or procedure?  controlling of new parameter?  hardware uniformity?  ??