Depending on who you ask, they're all usable.
A search will show recent forum activity on types and ratings, and the subsequent ignoring of mfr's recommendations by some.
This is the their whole list.
http://www.ascovalvenet.com/pdf/LiteratureRequest/ASCOTODAY_V7375R3.pdf
There are small brochures on each family of 4 digit numbers in pdf. form also.
NOTE: There is a difference in 'Solenoid Valves' and 'Fuel, Gas and Oil Products', in the blue menu on left of main page.
http://www.ascovalve.com/Applications/Products/Solenoid2WayData.aspx
This is the segment marketed specifically to control combustibles.
http://www.ascovalve.com/Applications/Products/FuelGasOilSolenoidValvesData.aspx
When I called I was advised to use the 8214 family. Specifically 8214G020 in 1/2"NPT. List =$130.
It's just not cheap and common on Ebay...
Others will say that the ones for inert gas, water and light oils are suitable.