What would be the best choice for lowest wear on engine timing chains?
The GM High Feature V6 (LLT 3.6L) made for the past 10 years has had some failures (stretching, elongation) and GM says its some combination of poor oil lubrication and materials needing hardening (carbonitriding was introduced after July 2010). Affected vehicles have been the Lambda chassis Acadia/Enclave/Traverse/Outlook, Cadillac CTS and ATS, 5th Generation V6 Camaros, Opels, Saabs, etc. Of course other engines suffer from this as well, some more than others.
What can be done to lube those chains better? GM issued recalls on past Traverse/Acadia/Enclave/Outlook/Cadillac LLT v6's to cause the OLM to call for more frequent oil changes. I know my 2011 Camaro v6 already came from the factory with the more-frequent oil change OLM settings, as this car drives me crazy with how much it wants OLM oil changes.
Are more frequent oil changes really the answer? GM says it is. However, maybe the managers at GM are ignoring findings that say wear rates are actually worse with fresh oil. Reference: http://papers.sae.org/2003-01-3119/
http://papers.sae.org/2007-01-4133/
"In one of our previous studies it was observed that engine oil samples collected from fleet vehicles after 12,000 mile drain interval showed 10-15 % lower friction and more importantly, an order of magnitude lower wear rate than those of fresh oils." ... "As in the previous study, the results showed [in this new field study with taxi fleets] that the aged engine oils provide lower friction and much improved wear protection capability. These improvements were observed as early as the 3000 mile drain interval and continued to the 15000 mile drain interval."
So whats the best strategy?
Is the high-moly Mazda 0w-20 (600 ppm moly) or Scheaffer 5w-30 synthetic (300 ppm moly) the answer? There are high-zinc ZDDP (with catalytic convertor destroying phosphorous) oils out there like Quaker State Defy 5w-30 synthetic blend and Royal Purple HPS 5w-30, along with Euro spec oils with high ZDDP. Are they the answer here?
Does the 4-ball wear test cited by Amsoil in their recent 5w-30 http://www.amsoil.com/lit/g3115.pdf comparison measure wear performance close enough for the kind of mixed-boundary-layer slapping, sliding, metal-to-metal interface between sprocket teeth and chain pins?
The GM High Feature V6 (LLT 3.6L) made for the past 10 years has had some failures (stretching, elongation) and GM says its some combination of poor oil lubrication and materials needing hardening (carbonitriding was introduced after July 2010). Affected vehicles have been the Lambda chassis Acadia/Enclave/Traverse/Outlook, Cadillac CTS and ATS, 5th Generation V6 Camaros, Opels, Saabs, etc. Of course other engines suffer from this as well, some more than others.
What can be done to lube those chains better? GM issued recalls on past Traverse/Acadia/Enclave/Outlook/Cadillac LLT v6's to cause the OLM to call for more frequent oil changes. I know my 2011 Camaro v6 already came from the factory with the more-frequent oil change OLM settings, as this car drives me crazy with how much it wants OLM oil changes.
Are more frequent oil changes really the answer? GM says it is. However, maybe the managers at GM are ignoring findings that say wear rates are actually worse with fresh oil. Reference: http://papers.sae.org/2003-01-3119/
http://papers.sae.org/2007-01-4133/
"In one of our previous studies it was observed that engine oil samples collected from fleet vehicles after 12,000 mile drain interval showed 10-15 % lower friction and more importantly, an order of magnitude lower wear rate than those of fresh oils." ... "As in the previous study, the results showed [in this new field study with taxi fleets] that the aged engine oils provide lower friction and much improved wear protection capability. These improvements were observed as early as the 3000 mile drain interval and continued to the 15000 mile drain interval."
So whats the best strategy?
Is the high-moly Mazda 0w-20 (600 ppm moly) or Scheaffer 5w-30 synthetic (300 ppm moly) the answer? There are high-zinc ZDDP (with catalytic convertor destroying phosphorous) oils out there like Quaker State Defy 5w-30 synthetic blend and Royal Purple HPS 5w-30, along with Euro spec oils with high ZDDP. Are they the answer here?
Does the 4-ball wear test cited by Amsoil in their recent 5w-30 http://www.amsoil.com/lit/g3115.pdf comparison measure wear performance close enough for the kind of mixed-boundary-layer slapping, sliding, metal-to-metal interface between sprocket teeth and chain pins?
