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Since we do love Rotella T 15w-40....
Phosphorus (a component of ZDDP - Zinc Dialkyl-Dithio-Phosphate) is the key component for valve train protection in an engine, 1600ppm ( parts per million) used to be the standard for phosphorus in engine oil. In 1996 the EPA forced that to be dropped to 800ppm and then more recently in 2004 to 400ppm again.
Valve trains and their components are now wearing out faster and this drop in phosphorus content has been a problem for many engines (especially those with flat-tappet type cams). Unfortunately, it's the second most destructive substance to shove through a catalytic converter. Since most of us don't have cats on our Burgies...well......
When the US government mandated a 150,000 mile life time on catalytic converters, the quickest way to do that was to drop phosphorous levels and bugger the valve train problem. Literally.
Shell Rotella T 15w-40 has also maintained a very high level of phosphorus have at least 1400ppm which is not classified as energy/fuel conserving oils and thus do not interfere with the precious government CAFE (corporate average fuel economy) ratings. This also means that they don't get the coveted ratings of other oils but they do protect your valve train. The same rule of thumb is true for racing oils like Royal Purple - because they're not classified as energy / fuel conserving, it would seem they still contain good quantities of ZDDP.
IF you were not aware, Rislone manufactures an oil supplement to boost the ZDDP content of your existing oil.
http://www.barsproducts.com/catalog/...treatment-4401
GM part number 12345501 oil additive (4 ounce bottle).
Since it doesn't do anything else to the oil besides increased ZDDP, it SHOULD not be detrimental to clutches, as it has 4-stroke motorcycle engine instructions as well.
But feel free to add to the discussion!
Just a little FYI for 2013
Phosphorus (a component of ZDDP - Zinc Dialkyl-Dithio-Phosphate) is the key component for valve train protection in an engine, 1600ppm ( parts per million) used to be the standard for phosphorus in engine oil. In 1996 the EPA forced that to be dropped to 800ppm and then more recently in 2004 to 400ppm again.
Valve trains and their components are now wearing out faster and this drop in phosphorus content has been a problem for many engines (especially those with flat-tappet type cams). Unfortunately, it's the second most destructive substance to shove through a catalytic converter. Since most of us don't have cats on our Burgies...well......
When the US government mandated a 150,000 mile life time on catalytic converters, the quickest way to do that was to drop phosphorous levels and bugger the valve train problem. Literally.
Shell Rotella T 15w-40 has also maintained a very high level of phosphorus have at least 1400ppm which is not classified as energy/fuel conserving oils and thus do not interfere with the precious government CAFE (corporate average fuel economy) ratings. This also means that they don't get the coveted ratings of other oils but they do protect your valve train. The same rule of thumb is true for racing oils like Royal Purple - because they're not classified as energy / fuel conserving, it would seem they still contain good quantities of ZDDP.
IF you were not aware, Rislone manufactures an oil supplement to boost the ZDDP content of your existing oil.
http://www.barsproducts.com/catalog/...treatment-4401
GM part number 12345501 oil additive (4 ounce bottle).
Since it doesn't do anything else to the oil besides increased ZDDP, it SHOULD not be detrimental to clutches, as it has 4-stroke motorcycle engine instructions as well.
But feel free to add to the discussion!
Just a little FYI for 2013