Here is a link to Dexos1 approved oils. Should be able to search the list for licensed HM oils if concerned. I however, would not have any issue running PPHM or M1HM in any vehicle that originally specified Dexos1 as I feel those two would easily meet the requirements.
http://www.centerforqa.com/dexos-brand1/
Also, here is the differences between Dexos1 and GF-5 oils. Dexos has a few items that are more stringent and why you don't see any straight conventional Dexos1 oils. Likely the cold flow and volatility requirements are why. My guess is this is to help DI engines which can be brutal on oil.
Features & Benfits
Compared to GF-5, the dexos™ weighted piston deposit (WPD) limit has been
increased from 4.0 to 4.5. This translates to „cleaner pistons‟ and better engine
performance. How? Piston deposits can form behind and around piston rings causing
the rings to stick and be “sluggish”. Full compression does not occur resulting in
increased emissions, decreased fuel economy and decreased engine performance
overall.
The dexos™ specification includes an aeration test on new and used oil. No such test
is included in the next generation, GF-5 industry specification. Sufficient aeration
control is a key criteria when the motor oil also functions as a hydraulic fluid, which
is the case in GM engines designed with Variable Valve Timing. Variable Valve
Timing (also referred to as cam phasing) is an increasingly common design in GM
engines to improve fuel efficiency.
dexos™ exhibits improved oxidation and wear performance:
o Improved oxidation means the oil better resists thickening. As an oil becomes
more viscous (or thickens), fuel economy is reduced. Oil thickening could
lead to problems in pumping the oil through the lubricating passages of the
engine resulting in engine damage.
The dexos™ specification includes a test for low-temperature pumpability. This sort
of test is not currently included in the next generation industry specification.
Although generally not an issue in warmer climates, if an oil becomes too viscous in
colder temperatures, adequate lubrication may not occur resulting in increased wear
and in severe cases, engine failure.
Oils meeting the dexos™ specification have more stringent volatility requirements
than the next generation GF-5 industry specification, meaning that the amount of oil
volatilized (or consumed during use) is lower. This performance requirement was put
in place to limit oil consumption over extended drain intervals.
