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Hey guys,

I have some fairly noob questions for you good fella's.

1997 Subaru Impreza Sportswagon EJ20 5sp dual range
It's been 6500km since last minor service (by me) in which I replaced the air and oil filters as well as the engine oil. The service before that at 147,000km was a Major service undertaken by professionals. (Car now has 158500 )

I would like to change the gearbox, engine and diff oil (K&N filter still going strong, will clean it with air compressor).

My questions are:

1.Where is my Gearbox filler?
2. How much oil?
3. Oil recommendations?
4. I presume this also covers my front diff? Same case?

5. How to change my rear diff oil?
6. Oil recommendations?

7. Oil recomendations for the noise factory? Fairly sure I used some motul semi synth stuff last time around, I hear contrasting stories on whether full synth is good or bad for Subaru's. .

8. Any additional treatments or things I should/could do check/perform?

Thanks in advance guys. I did have some trouble with search, hence the thread

Hey mate,

Your K&N should be cleaned with cleaner spray and low pressure water from the tap. And only lightly oil it on the underside.

I don't have a manual so will leave the rest for someone else to answer.

You only need to change the gear box and diff oil about every 50,000Km, Gearbox dip stick on drivers side of the box is also the fill point, so drain from bottom overnight, preferably start with the box hot as more oil will come out then put bung in and get a funnel with a bit of thin tube and re-fill............. rear diff, undo bottom plug and empty then put back in and undo top plug and fill to bottom of that hole. I think the box is around 3L and rear diff about half a L but google it.

Oiled air filters are crap on Subaru's, especially K&N as they can deposit oil on your air flow meter which can either kill it or make the car run like a pig, a worthwhile suggestion is to buy some Contact Cleaner and give the AFM a spray every service.

Bradenrm wrote:1.Where is my Gearbox filler?
2. How much oil?
3. Oil recommendations?
4. I presume this also covers my front diff? Same case?

5. How to change my rear diff oil?
6. Oil recommendations?

7. Oil recomendations for the noise factory? Fairly sure I used some motul semi synth stuff last time around, I hear contrasting stories on whether full synth is good or bad for Subaru's. .

8. Any additional treatments or things I should/could do check/perform?

1. Dip stick tube
2. 3.7 ltrs
3. Castrol VMX80 (is my personel choice but I sell Motul at the workshop)
4. Correct
5. Remove both plugs and drain, then refit bottom plug and fill till it comes out the top plug hole. Should be around 1 ltr
6. Motul
7. Semi-synth is fine for your open diff. I just wouldn't use fully synth but any 80/90 weight oil will be fine. Just remember to replace in 50,000kms.

Always remove the filler plug first

Thanks heaps guys. I'll keep all the above in mind when diffs and gearbox is due though that will be the 200k service so may need timing belts done, and I may leave that to the pros unless I get all the required tools.

I ended up changing the oil and oil filter, cleaning the air filter as per K&N instructions, and sprayed the MAF with MAF cleaner.

I also had all the exhaust heat shields cut off (except the two on the headers coming right off the exhaust ports, they're structural apparently). The reason was they were rattling at 3100-3250rpm which is 100km/h 5th gear so rather annoying.

While they were there I had them replace the exhaust from the cat-back. Part of the tube was rusted and caved in along the seal, which I fixed with putty and exhaust tape..however it started to break again.

So it's now got a 2 inch cat back with a sports muffler...NOT a wog can. It's oval shaped. And now it's too loud for my liking though it sounds great lol.

All of the above done, seems to be driving much nicer

Worth noting that I ended up using an engine flush, which was 450ml.
With this plus the oil in the engine, the quantity that I got out was bang on 4l. When I filled it last I slightly overfilled it so it's burned/dropped about 600ml oil in 6500km. Is this bad?
I think it may have been the bottom hose on the radiator? But i degreased under the whole car anyway and will monitor for leaks

Went with Penrite 10w50 Fully synth.

Oil consumption at that rate is great, when I bought my Liberty Exhaust I paid nearly $2,000 for it and hated it because it was so noisy, within a few weeks it was one of the best sounding ever, just give it time to carbon up a bit.