TRD struts/shocks re oil ??

[AND189]

Gday all,
2008 i got my yaris at 20,000 km i installed the trd springs struts and shocks after a 5,000km i then installed the strut brace and sway bar the care has just done its 60,000 and i am looking to modify the trd shocks and struts by replacing the oil to a higher grade the old man said he used to put grease in his wether or not that is going to help corner speed at all i dont know,
so the thing i am after is corner speed being able to hold it in through the corner right now i have the trd kit strut brace sway bar and i have 195/50/R15 wheels with Bridgestone POTENZA Adrenalin tyres. so is it posable to replace oil in struts and if so will it make a big difference