UNIT NUMBER: 01 CHEVY
EQUIPMENT MODEL: 8.1L 496 CI V-8
FUEL TYPE: Gasoline (Unleaded)
OIL USE INTERVAL: 2,161 Miles
OIL TYPE & GRADE: Mobil 1 10W/30 (Gas)
MAKE-UP OIL ADDED: 0 qts (sump capacity 7QT)
Blackstone comments: We would not expect this very slight level of coolant to cause the bearing wear found last time. This oil was
in use about 1/3 the miles of the last sample, and lead and tin came right down, which is good. Lead is still
reading high, but some of it in this sample is residual from the last oil in use. We would expect to find Dexcool
in the potassium and sodium levels, and the 7 ppm sodium we found is really not enough to show a problem. We suggest
running the next oil 2200 miles and resampling for another look. Maybe lead will continue to drop!
Last UOA Blacksone mentioned the sodium levels as a possible coolant leak indicator. but the coolant test came up neg, with this sample I asked if a small coolant seep (one so small that did not show on the coolant test) would cause bearing wear like that, I also asked weather their coolant test can detect GM Dex-cool. That should shed some light on Blackstones coments. The sodium level is actually in line with what comes in with the M1, and it actually drops as it is in the engine. The potassium is very low, I looked at a few other UOA's and it seams in line with many other vehicles. The coolant tank level has not dropped, the system holds pressure even if left to sit for 36 hrs, I either have no coolant leak or such a small leak that it is un-important. it cannot be sensed anything at my disposal.
This is my only vehicle so it sees a varied work load, mainly 30mile one way freeway daily commute, some local suburban driving (groceries etc). On this OCI one 4,000 pound tow to Tennessee and back (should be nothing for this HD truck), 2 bottles of Chevron Techron concentrate were added to the fuel near the beginning. No other additives to the oil or gas were used. This sample was taken just before installing a bypass filter, the oil was not changed, no TBN because I would assume the oil is still plenty strong after only 2,000 miles. The TBN made the 6k OCI just fine
At first glance the lead looks a lot better but if you look at the # of miles it actually looks the same, this shows that it was not a problem of worn out old oil not protecting as the lead wear is still happening right after the oil change, 18 x 3 is 54 dillute with one qt of makup oil and it is close to the 51ppm of the 6k OCI, I am starting to think the truck may have a defective bearing
I am going to take this oil to 4k sample and see what the bypass filter can do, and then try the thicker GC this winter and a HDMO this spring when it warms up, see if it helps but I doubt it,
GM ****** me
This is on top of the Piston slap that started @ 250 total miles that they refused to fix
[ November 20, 2003, 04:34 AM: Message edited by: RavenTai ]
EQUIPMENT MODEL: 8.1L 496 CI V-8
FUEL TYPE: Gasoline (Unleaded)
OIL USE INTERVAL: 2,161 Miles
OIL TYPE & GRADE: Mobil 1 10W/30 (Gas)
MAKE-UP OIL ADDED: 0 qts (sump capacity 7QT)
Blackstone comments: We would not expect this very slight level of coolant to cause the bearing wear found last time. This oil was
in use about 1/3 the miles of the last sample, and lead and tin came right down, which is good. Lead is still
reading high, but some of it in this sample is residual from the last oil in use. We would expect to find Dexcool
in the potassium and sodium levels, and the 7 ppm sodium we found is really not enough to show a problem. We suggest
running the next oil 2200 miles and resampling for another look. Maybe lead will continue to drop!
Fresh oil values taken from Mobil 1 Virgin Oil Analysis Compendium . But I think Mobil has tweaked the formula since then including thickening it
Last UOA Blacksone mentioned the sodium levels as a possible coolant leak indicator. but the coolant test came up neg, with this sample I asked if a small coolant seep (one so small that did not show on the coolant test) would cause bearing wear like that, I also asked weather their coolant test can detect GM Dex-cool. That should shed some light on Blackstones coments. The sodium level is actually in line with what comes in with the M1, and it actually drops as it is in the engine. The potassium is very low, I looked at a few other UOA's and it seams in line with many other vehicles. The coolant tank level has not dropped, the system holds pressure even if left to sit for 36 hrs, I either have no coolant leak or such a small leak that it is un-important. it cannot be sensed anything at my disposal.
This is my only vehicle so it sees a varied work load, mainly 30mile one way freeway daily commute, some local suburban driving (groceries etc). On this OCI one 4,000 pound tow to Tennessee and back (should be nothing for this HD truck), 2 bottles of Chevron Techron concentrate were added to the fuel near the beginning. No other additives to the oil or gas were used. This sample was taken just before installing a bypass filter, the oil was not changed, no TBN because I would assume the oil is still plenty strong after only 2,000 miles. The TBN made the 6k OCI just fine
At first glance the lead looks a lot better but if you look at the # of miles it actually looks the same, this shows that it was not a problem of worn out old oil not protecting as the lead wear is still happening right after the oil change, 18 x 3 is 54 dillute with one qt of makup oil and it is close to the 51ppm of the 6k OCI, I am starting to think the truck may have a defective bearing
I am going to take this oil to 4k sample and see what the bypass filter can do, and then try the thicker GC this winter and a HDMO this spring when it warms up, see if it helps but I doubt it,
GM ****** me
[ November 20, 2003, 04:34 AM: Message edited by: RavenTai ]
