The manuals were printed before GM came out with the blue fluid to fix the AWD and Autotrac transfer cases failing in 99 (mainly in AWD due to always on). The dealers are kinda clueless on this - the improved fluid should be able to be run in any case would be my opinion. This blue syn fluid was to solve clutch binding and wear and added friction modifiers per GM. The only risk I have read about on all syn fluids is long term RTV breakdown and this mainly applies to rear ends with no gasket, only RTV.