I just changed the transmission oil and rear differential oil on my 97 OBW with 128 000 miles. I have a few questions for those that have done this before. First question is: Should there be a sealing washer on the transmission drain plug? Mine did not have one and I tried one of my engine oil drain plug washers but it was too small. So I put it all back in without a washer and filled it with redline 75-90NS oil, but now I'm wondering...

 

2nd question: The transmission oil looked fairly clean but the rear differential oil was quite dirty. Is that normal? Nothing unusual was on the magnetic drain plug.

 

last question: I just used some teflon tape to seal the rear differentail plugs. Any problems using that.

 

Thanks

1: yea thes a washer spupost to be on the drain plug its larger than the engin sump plug washer.

 

2: normal

 

3: yeah thats fine but unnessary unless leaking they are tapered so they seal

Thanks. Is the mating surface on the transmission case where the oil drain plug seats flat or rounded? Mine was rounded which kind of puzzled me as I have never seen that on any of my other cars. I'm wondering now if the old crush gasket was stuck on the case realy hard. On the drain plug I could see where it was only contacting that rounded mating surface.

Hey Pascal,

 

It should be a flat washer. Good luck.

 

Hieu

Thanks Hieu,

 

That is what I was affraid of. I guess I will just keep an eye on it and hope it does not leak. It did not leak before I changed the oil, and there was no sealing washer. I will definately get a sealing washer for next time. Had I not used the Redline oil I would just change it out again and put a sealing washer in, but that Redline oil is expensive stuff.

Get a washer, drain the fluid into a clean pan and pour it in again after sealing the bottom correctly.

 

I'm a worrying kind of person.

Q2: On my 2002 MT Forester, I drained the rear-diff oil at 1000-km, and it was a 'dark-grey' opaque colour.

I drained it again at 8000-km and at 50,000-km, and each time the oil was clear.

Q2: On my 2002 MT Forester, I drained the rear-diff oil at 1000-km, and it was a 'dark-grey' opaque colour.

I drained it again at 8000-km and at 50,000-km, and each time the oil was clear.

 

Break-in is harder on the fluid now it stays cleaner!

OR, the Subaru fluid was different??

 

Although break-in does affect it.

My rear differential oil was dark and thick. I'm glad I put the Redline synthetic in there. Might help on fuel consumption especially in the winter. I was realy taken by surprise how much more gas it took in the winter. More winter/summer difference than any other car I have owned.