I called Amsoil, I got this info back;
<span style="font-weight: bold"><span style="font-style: italic">LUBRICANTS & FLUIDS
Engine Oil
Grade 1......SJ
Synthetic 5W-40 European Engine Oil
SAE 10W-40 Synthetic High Performance Motor Oil
SAE 10W-40 XL Synthetic Motor Oil
-4 to 61°F......10W-30
Above 32°F......20W-40, 20W-50
Above 14°F......15W-40, 15W-50
Above -4°F......10W-40, 10W-50
Below 14°F......5W-20, 5W-30, 5W-40
Manual Transmission,.....GL-4
Below 0°C......80W
Synthetic Manual Transmission and Transaxle Gear Lube 75W-90
Manual Transmission,.....GL-4
90
Synthetic Manual Transmission and Transaxle Gear Lube 75W-90
Differential, Rear .....GL-4
Below 0°C......80W
Synthetic Manual Transmission and Transaxle Gear Lube 75W-90
Differential, Rear .....GL-4
All Temps......90
Synthetic Manual Transmission and Transaxle Gear Lube 75W-90
Fluids
Brake Fluid.....HB
Series 500 High Performance DOT 3 Brake Fluid
Clutch Fluid.....HB
Series 500 High Performance DOT 3 Brake Fluid
CAPACITIES
Engine, without filter..........4.2 quarts[1]
Cooling System, Initial Fill..........4.8 quarts
AMSOIL Antifreeze and Engine Coolant
Manual Transmission, W/O OD..........1.7 pints
Manual Transmission, W/ OD..........3.2 pints
Differential, Rear..........1.3 pints</span></span>
So I guess I should do a full fluid change as well. This still dont convince me that 5w30 is too light, as its listed in the Cold Temps, but Since I only drive on nice hot days I'll still change it, tranny too it seems.