I was scouring NASIOC looking for anwers to what transmission oil or cocktail is best for the STI 6 speed, and ended up with no definate answer, and it appears that Uncle Scotty's cocktail is 5MT specific. Uncle Scotty replied to the PM I sent him on NASIOC confirming this, and saying to stay away from synthetics in the tranny. ( His PM reply is below ) I am asking those driving Subaru 6MT cars, what kind of lubricant are you using, for how many miles, and what is your experience with it? I noticed different camps that had an agreement on the following points about the Subaru transmissions. * GL5 (pressure rating) grade oil is a Subaru requirement for the front transaxle * The front transaxle and transmission lubricate with the same oil * Synchro's and other tranny parts in the 6MT are made of brass * High pressure GL5 lubricants tend can corrode brass or yellow metal parts * Synchros require a lubricant that's not too slippery so they will work well * The center differential is a sealed unit and not a factor in this matter So it seems like there is a conflict between the GL5 pressure grade for the transaxle and the yellow metal transmission components that requires a trade-off when selecting a lubricant. I've also read reports of gear grindage with the Subaru OEM fliuds, which I think are dino based. In Scotty's reply he references NASIOC Porter ( Jason's Porter's) recommendation for OEM fluids. --- Scotty's reply below ----- I can make NO recommendation for the 6mt other than buy and use the Subaru stuff member 'Porter' posted about in one of the threads(in the Maint. forum, IIRC)....he posted the subaru PN....and it 'aint cheap....but mebbe ya can find someone to split it with ya. THAT would be what I would buy if I had the 6mt, no doubt. DO NOT use any 'synthetic' lube in yer tranny----bad juju. Uncle I was able to dig up the part numbers and a resource for the OEM fluid. Would anyone know what SoG uses for their tranny and rear diff lube, and if they can sell it by the litre or quart? 04+ Subaru STi 6spd Transmission fluid - Part#: K0323AA093 -- 9.30 per/quart (FLOW Subaru price) *04+ Subaru RLSD fluid -- Part#: K0305Y0900 -- 23.87 per bottle (1 qt, I believe) * - There is a TSB out now stating to replace with this fluid. WJM states that NOT using this will KILL your rear diff. PM WJM for more technical information relating to this. Unfortunately, this is a BULK order the dealership has to do (5 gallons worth of tranny fluid!). If you would like the CORRECT transmission fluid and would to like to NOT have problems with your transmission, CALL Mary Hall at Flow Subaru FAX336-725-3554). TOLL FREE 1-800-489-3534. She will hook you up with any specified amount of tranny fluid you need, and just tell her to give you the $9.30/qt price as seen on NASIOC. The reason this is big is that almost all dealerships DON'T stock this fluid, and it is realtively hard to get the RIGHT fluid.
Yeah. They say that transmission is bulletproof when it comes to drag and stuff but I'm sure that's only if you use the right fluids.
I'm using Extra S GL5 subaru fluid. Got it here in town from SoG. There's another factor in picking a fluid for your 6 speed if you have a DCCD. The clutch plates in the DCCD will chatter pretty badly if you pick the wrong fluid (IE something without the correct additive package).
Thanks Veck! I'm wanting to gain a better understanding of the STI transmission setup. Does this mean the entire DCCD and center differential shares the same fluid with the transmission and front transaxle on the STI, or just the controller/actuator portion of the DCCD? I'm trying to understand if the center diff is a sealed unit or not on the STI. Also can we get it it by the liter/quart or do we have to bulk order it?
SoG will sell you as much or as little as you need as long as you bring your own container. The front diff, transmission gears and DCCD mechanism all share the same fluid.
Thanks for the info Veck, I'm glad I didn't go and throw in some synthetic in there without researching. My car is about at 6000 miles now. Would it make since to change the tranny and rear diff to remeve any break-in metals that may be in the case?
the 6 speed has a magnet on the inside of the little oil pan on the bottom. If you really want to get any metal fragments out you will need to drop that pan, clean the magnet and put it back together. Kind of a pain since it does not use a regular gasket (uses RTV type sealant)
I read about the cocktail back when i had my original 5 speed. Decided not to use it as I had some warranty left. When I upgraded to the RA box i went with Neo or Redline and never had a single problem.
I'm a little curious about the alternatives to the stock stuff for the 5MT. I'm not too keen on the cocktail thing but only because I want to have the dealership change it for me. Sure I could do it but they know their shit and will be more likely to get it right. Anybody got a link to some info about synthetic fluids, not mixtures, for the 5 speed?
What weight is the factory fluid?I just got some from Troncalli Sub.and saw that the receipt said 80w140.Called parts and they said this was the latest greatest stuff.
I dont think you should use 80w-140 75W-90 was what ive been reading Im keeping an eye on results and will change when i hit 20k Im still using factory oil in the tranny and Amsoil in the rear diffs
I was using Valvoline 75/90W for 20,000 miles in my 6MT 04 STi tranny; but was having problems with it shifting smoothly when cold... light grinds, difficulty getting it into gear, etc. Just switched back to the stock "Extra-S" tranny fluid and it made my tranny shift like butter. A+ recommendation from WJM!
anything 75W-90 for the 6MT is fine. I'm pretty confident I could put vegetable oil in mine and it would hold up fine. the damn thing is strong
Its not a matter of the weight, its the ADDITIVES in it that make it SHIFT well, the ADDITIVES that enable the gears to be lubricated properly, and the ADDITIVES that make all of the other additives work together. Using anything else in the 6MT results in a very un-good shifting experience. The Extra-S is 'synthetic' Group 3 oil and is 75w90. As for the rear LSD for the 04 05 06 STi...the LSD oil from SUBARU has special shit in it to keep the mechanical LSD working correctly. Its 90w. I dunno anything about it other than using non SUBARU LSD oil will fuck it up pretty badly.
I use a synthetic gear oil with differential additives for my rear diff. it's a suretrac R160 3.90. for the tranny I use dino 75-90 with differential additives. subaru doesn't make moon additives only they can get, but we don't know exactly what goes in their oil. any idea who it's made by?
I'm one of the disbelievers with regards to the Uncle Scotty's cocktail. Especially in colder weather its seeming to take longer to warm up and added too much shifting effort to the tranny. Transmission feels worse if anything, I had a grind going into 3rd and now it feels more like a grind coming out of 2nd, just moved the effort around. I'm going back to the OEM stuff in another year but I spent too much money on the cocktail to just dump it out since it works fine.