Today we use Aero Shell W100, not sure what they used in WWII though. Hope that's some sort of help.I have a Rolls Royce Griffon, I looked up the oil it said "100 S.U. (D.E.D.2472B)" Can anyone tell me what wt of oil this is? I believe it is either 30wt or 65wt, Thanks for your time.
Thank you so much!DED.2472A / 80 / cold weather, 32°F/0°C or below / Aeroshell 80, Intava Grey Band
DED.2472B / 100 / normal temperate conditions / Aeroshell 100, Intava Red Band, Texaco 467, Caltex 467
DED.2472C / 120 / used for extreme tropical summer / Aeroshell 120, Intava Green Band, Texaco 468, Caltex 468
NOTE the "100 S.U." in your post above stands for a viscosity of 100 using the Saybolt Universal method.
The Saybolt Universal Viscosity (SUV) or Saybolt Universal Seconds (SUS) or Saybolt FUROL Viscosity (SFV) value is the time in seconds required for 60 cubic centimeters of a fluid to flow through the orifice of the Standard Saybolt Universal Viscometer at a given temperature under specified conditions.
The WWII British DED.2472 specification for oil viscosity used a temperature of 210°F/100°C, as does the standard SAE test.
Hence the SAE equivalents are as in the reference posted above by Simon Thomas, ie:
DED.2472A / 80 is ~SAE 40
DED.2472A / 100 is ~SAE 50
DED.2472A / 120 is ~SAE 60
NOTE, however, that SAE oil grades with a W in them (10W-40 for example) have been blended and/or tested to give a cold weather or Winter (hence the W) performance number (the 10 in the 10W-40 for example). The 10W-40 designation indicates that the oil meets the standard for SAE 10 viscosity oil at cold temperatures and the standard for SAE 40 viscosity oil at 210°F/100°C.