The system was designed for PAG 46. No advantage to using higher viscosity. I'd just stick to what it calls for. Itd be like putting 15W40 in a motor that calls for 5W20
'01 Crown Vic. P73. 145k. Ex college president's car.
Mods so far:Bumper tuck, Sony Xplod head unit, sidemarker blink mod, New OEM headlight housings from ADTR, BH1976 Headlight Relay Harness, $40 junkyard 70mm TB (More to come as $$$ permits)