mine also like this... had to top up frequently...i think got leaking somewhere.... for now keep 1 bottle brake fluid spare inside the car...

for ur  gear oil use mitsubishi diaqueen~ 

ard rm150 including labour~   

10w-40 or 20w-50 are simply the viscosity grade, or rather 'weight' of an engine oil. 10w-40 should do fine. Currently running on Castrol Magnatec.

lienage:
not all old engine above 8yrs can use 10w40,ok?
dun b always so smart suggesting ppl use only 10w40 cuz if there's anything happen then d car will stay in workshop for overhaul~
for 8yrs n above i'll suggest use 15w40 or 15w50 due to piston ring is old n getting worn out~
my 4G92 now using 15w50 due to my engine is old n consuming engine oil 15w40

my own understanding of the oil viscosity is like this.
20w =  thick oil , for engine that consumes engine oil
then 0w = thin oil, for those who wants more roar from engine. and better FC.

40 = the max temp that the oil can maintain its viscosity, normally NA engine can use this.
50 = higher max temp, for high rev engine, or turbocharged.

i would recommend, if your car doesnt 'eat' engine oil. then go for 10w-40.
if not, go for 15w, still cannot, 20w lo..

what engine??.. evo ah??...

1. 4-2-1 exhaust extractor.
2. remove cat-con.
3. change to bigger muffler.
4. use platinum and above spark plugs.
5. use 10w-40 engine oil or 5w-40.
6. use STEEL RIM only.
7. change driving habit. (try not to keep doing acceleration, maintain constants speed above 60kmh.)

8. change to MANUAL GEARBOX if possible.**

this is my own opinion la.. see what other sifu may say.

For starter, just change the whole exhaust system from head to tail. I'm using 1.5 AT, of course 1.5 has poor fc but it sure improves after I did full exhaust system. You can go to any exhaust shop, or you can browse through LYN automotive garage. There are few specialist. My setup is 4-2-1 extractor, remove the mid box change with bullet, 1.6" piping size, and s-flow muffler. As long you maintain your driving style, you will see the mileage improvement. Top speed also improve

Not sure, depends on your setup. Not more than RM 1k, or if you go for better extractor branded ones, might go slightly above that.
To me it's not noisy. S-flow muffler is quieter and maybe has a bit sporty sound. Straight flow the sound louder, and to some yes it is noisy.

brand is depending on ur budget too~
make sure u got enuf budget to change good 1 instead of cheap/cap ayam then u complaint later  tis n tat~

average ard 600-900 

I did mine RM 700 So far fc improve around 30%, fully satisfied although 1.5 has poor fc. Got more money, change to 1.6