I've brought the correct oils, now going to change the gearbox and diff oil on my MY03 JDM Sti- can anyone give me any advice or tips that might help?? Do I need to replace any washers on the plugs when re-inserting?? thanx.

 

No the old washers will be fine, you must make sure the car is on level ground, when you measure the gear box oil, filling it up is fun, I bought a large oil syringe from Halfords with a flexible pipe fitted to the end, this saved a lot of mess, as you have to fill through the gear box dipstick hole.

The rear diff plugs, tend to be very tight as they have a taper thread, so a big bar may come in handy. Fill rear diff on level ground, until oil starts to weep out of the top filler hole.

 

Don't forget - the 6-speed box has two drain plugs. One under the centre diff. (which you can see easily) and another in a small sump at the bottom of the gearbox. This will require the removal of the small plastic cover.
JohnD