According to there spec ther is only one Mobil DTE Light

Named Series Mobil DTE Light Mobil DTE Medium Mobil DTE Heavy Medium Mobil DTE Heavy
ISO Viscosity Grade 32 46 68 100
Viscosity, ASTM D 445
cSt @ 40º C 31.0 44.5 65.1 95.1
cSt @ 100º C 5.5 6.9 8.7 10.9
Viscosity Index, ASTM D 2270 102 98 95 92
Pour Point, ºC, ASTM D 97 -18 -15 -15 -15
Flash Point, ºC, ASTM D 92 218 221 223 237
Density @15º C kg/l, ASTM D 4052 0.85 0.86 0.87 0.88
TOST, ASTM D 943, Hours to 2 NN 5000 4500 3500 2800
FZG Scuffing, D51354, Fail Stage 8 9 10 10
Rust Prevention, ASTM D 665:
Distilled Water Pass Pass Pass Pass
Sea Water Pass Pass Pass Pass
Water Seperability, ASTM D 1401,Min. to 3 ml emulsion @ 54ºC 15 15 20 30
Copper Strip Corrosion, ASTM D 130,3 hrs @ 121º C 1B 1B 1B 1B
Foam Test, ASTM D 892, Seq I Tendency/stability, ml/ml 20/0 50/0 50/0 50/0
Air Release, ASTM D 3427, 50º C, min