Not the reference I was looking for, but:
M.T.72 coloured orange or yellow, issued in UK for all B vehicles, carriers, generating sets and small engines.
M.T.80 coloured red, issued in UK for A vehicles except carriers, and overseas for all vehicles.
Petroleum Spirit undyed, issued overseas for generating sets and small engines. Forbidden from use in vehicles.
Derv for use in C.I. engines.
Use of MT72 and MT80 necessitates daily check of engine compression. Any suspected lack of compression to be reported immediately (which ties in with what Richard was saying about valve problems).
From the RAMTS March 1945 "General Principles of MT"