what diff oil for 2005 sti? 90ls or 75w90
 

hi guys
im a newbie to the forum & i just wondered if anyone can point me in the right direction.im having abit of trouble finding the recommended oil for the rear diff on my 05 sti,iv read many threads & contacted various specialists & also subaru at nottingham & the answers iv had puzzle me.the owners handbook states gl-5 75w90 except sti with dccd with a temp chart,then at the side another temp chart with 90 in the arrow stateing sti version with dccd.iv been advised i should be using a 90LS oil as the diff is lsd & needs the LS oil as it is mineral oil-based & contains friction modifiers for the clutches in the rear diff,but after ringing scooby clinic,graham goode & subaru iv been advised 75w90 semi synthetic,75w90 synthetic 75w80 semi synthetic with no mention of it needing the LS propertys & 90LS.can i use a GL-5 75w90LS oil or should i be using just 90LS & should it be semi synthetic or fully syn? any info would be helpful
cheers jay

90w Motul or Fuchs very good :)

thanks 53WRX,is that the motul 90pa? how can these so called specialists get it so wrong,it beats me when they should have access to all the correct info,especially a main dealer,know wonder theres so many folk with premature diff wear & other issues.

With the diffs in the Impreza, the oil does not have to be limited slip specific as long as it's a 75w-90, 80w-90 or SAE90 GL5. Things like the Motul 90PA and Fuchs Gear 90 LS are good choices, but being mineral based, don't last as long as full synthetics.

Cheers

Tim

thanks tim for for your input,just a couple of questions,would the sae 90 mineral based oil need changing alot sooner say 15-20k & would it cope with a winter like we just had?.would the REDLINE Synthetic Gear Oil 75W-90 GL5 or the Silkolene SILKTRAN SYN 5 75W-90 be a better choice?
thanks again cheers jay.

Hi Jay

Those oils would cope with the winter fine, but the Redline or Syn 5 would be a better choice if you want the best protection.

Cheers

Tim

thanks oilman,all info's much appreciated.
cheers jay

Will Motul Gear 300 Gearoill SAE 75W-90 be OK for both front diff/gearbox as well as the rear diff?

The car has suretrack LSDs front and rear, non DCCD.

According to the data I have, it should be fine.

Cheers

Tim

MY05+ owners manuals state 90w oil for all MY05+ rear diffs :)

In that case, why would anyone use anything else? :freak3:

FYI, my question was clarified with a phonecall to AP who told me that AP never made the differentials for the Impreza, in fact Fujitsu Heavy Industries bought the whole project from AP years ago and manufactured them in Japan.

He said because it is not a plate diff I should use a normal oil with the grade the manufacturer suggests.

So I will go with 75W-90 that the japanese maintenance book suggests, the same as the front diff.

At last I got there.

Make sure you get this right. I put the wrong oil in mine and it was awful clonking and making strange noises. It didn't feel right it was locking up when turning. Changed it for motul 90Pa and has been fine ever since. Mine is a jdm my05 STi with dccd.

Take my advice mate I have been there and done it.

Btw it was 75w-90 that caused all my problems.

Thanks.
Yours has DCCD and helical diffs, mine's not DCCD and has Suretrac diffs.
The title is confusing, I should have opened a new thread and not posted here as it may confuse people.

According to the japanese manual
Attachment 55291
which translates to
Attachment 55292

For >2005 cars with DCCD though you are right, the correct oil to use is 90 (as the above manual also indicates).

Just want to thank 53 and dibbleyuk for their posts. Read this a while back and realised I had put 75w90 LS oil in my rear diff thinking it was the correct spec. Few weeks back I switched to motul 90Pa and the odd clonking noise and wheel scuffing when pulling away have gone. Well pleased :D :D

Glad I could help! I honestly thought my diff was on its way out and being a JDM and having different ratios I was expecting a long wait to find one luckly it was just the oil. :)

Ive run a 90pa in all my sti's seems to prefer it to the 75w90
Jay

Which oil for a 2002 Bugeye WRX

would you use 75w 90 as recommended or would it be beneficial to use 90LS

So use 90 in my rear diff and 75/90 in the box in my STI?
This may be reason of my strange noise I have when parking on full lock,only does it when hot! See my thread on weird noise.