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**Bob B.** · 07-28-2020, 01:47 AM

Dexos is not an additive, it is a set of oil specifications that an oil must meet to be approved for use in late model GM gasoline engines. Came out around 2011. A Dexos approved oil may be semi- or full synthetic, and many premium motor oils meet Dexos specifications. Mobil 1 5W-30 is a Dexos approved motor oil. So is O'Reilly's 'house brand' 5W-30 full synthetic.

07-28-2020, 01:47 AM	#6
Bob B. Senior Member Join Date: Aug 2005 Location: Los Angeles Posts: 1,312	Re: New LS owner...oil questions..Dexos 1... Dexos is not an additive, it is a set of oil specifications that an oil must meet to be approved for use in late model GM gasoline engines. Came out around 2011. A Dexos approved oil may be semi- or full synthetic, and many premium motor oils meet Dexos specifications. Mobil 1 5W-30 is a Dexos approved motor oil. So is O'Reilly's 'house brand' 5W-30 full synthetic. __________________ 1967 GMC CM-2500 Camper Cruiser, 351E V-6, NP 435 4 speed, Dana 60, and factory A/C. 2012 GMC K-3500 WT regular cab, 6.0L Vortec, 6L90.