5MT Tranny Fluid

Has anyone switched over to Redline GL-5 fluid in the LGT yet? I have read a couple posts on here where people said they had problems using it in WRX's but nobody gave any details. It meets the GL-5 requirement in the manual so as far as I'm concerend it should be fine?

The problem is that the fluid the tranny wants is different than what the front differential wants. Unfortunately, they share the same sump. A syncronized transmission works best if the fluid offers a little friction. The front diff. wants a more slippery fluid that is loaded with extreme pressure additives to prevent wear/breakage. So if you use a fluid that makes the tranny's syncros work better, you put the diff at risk. If you use the right lube for the diff, you might not experience optimal shifting. The GL-5 spec lube is optimized for the differential. GL-5 contains more EP additives than the GL-4 spec which tends to work better in trannies. If you want to use Redline, their 75w90ns would be the best choice. It is GL-5 rated, but does not contain a friction modifier (FM's usually are additives that make an oil more slippery, although there are some that do the opposite). Some people have reported some success with this fluid in their WRX's and STi's. Personally when I get to changing my tranny fluid in a couple thousand miles, I'm going to go with Chevron Delo ESI gear oil 80w90. It is a highly refined dino oil that is intended for heavy duty trucks. What I find appealing is that it has a non sulphur based EP add. pack. Sulphur EP adds can attack the soft yellow metals in the syncros. Since the Chevron gear oil is some pretty stout stuff and I'm amply confident in it's ability to protect the diff, I'm going to add 1 qt of Pennzoil Syncromesh. This is a specialty fluid that is designed for some GM manual trannies. It'll cut down the amount of EP protection a touch, but should make for smoother and faster syncro action. I'll let you guys know how it works out when I get around to it.

That only matters if the front differential is a clutch type or cone type limited slip and the Legacy has an open front diff. Whatever you choose, make sure you use something that is rated for limited slip otherwise your syncros on't work properly. The ONLY benefit you can expect from synthetic tranny fluid is easier shifting in very cold weather during the first few minutes of operation.

Why not use the same as factory fill, which is presumably Valvoline? If you do a google search on Subaru trans oils, you will discover in looking at 100s of forum threads that the Subaru transmission is very finicky about the brand and weight of oil used. Proceed with caution.

[quote name='rao']That only matters if the front differential is a clutch type or cone type limited slip and the Legacy has an open front diff. Whatever you choose, make sure you use something that is rated for limited slip otherwise your syncros on't work properly. The ONLY benefit you can expect from synthetic tranny fluid is easier shifting in very cold weather during the first few minutes of operation.[/QUOTE] I'm sorry, but this is 100% wrong. The fact that the LGT has an open front diff. means that you can use any GL-5 gear oil, it doesn't matter if it has limited slip friction modifiers or not. Also, limited-slip gear oils contain friction modifiers to make them MORE slippery. This is need for a clutch-type diff to avoid chatter. While this type of gear oil certainly won't hurt the front diff, the syncros in the tranny will hate it. You actually want to AVOID gear oils that are intended for limited slip differentials, as the friction modifiers will make the oil too slippery for the syncros to grab.

I've been using Quaker State Synthetic 75W-90 for about 4k miles without any issues. Smooth as silk...Still needs to warm up for a couple minutes when really cold though.

[quote name='Boostjunkie']I'm sorry, but this is 100% wrong. The fact that the LGT has an open front diff. means that you can use any GL-5 gear oil, it doesn't matter if it has limited slip friction modifiers or not. Also, limited-slip gear oils contain friction modifiers to make them MORE slippery. This is need for a clutch-type diff to avoid chatter. While this type of gear oil certainly won't hurt the front diff, the syncros in the tranny will hate it. You actually want to AVOID gear oils that are intended for limited slip differentials, as the friction modifiers will make the oil too slippery for the syncros to grab.[/QUOTE] You said exactly what I said. Different companies describe "friction modifiers" and what they do differently. The point is that you don't want to use a fluid that is too slippery or else the syncros won't have enought traction to work. Also, we agree that the GT has an open front differential.

FYI, Cobb Tuning sells the Redline 75W90NS: [url]http://cobbtuning.com/legacy/drivetrain2.html#gearoil[/url] That being said, I'd trust that a Redline fluid swap out would be fine for the LGT. I seriously doubt Cobb would sell something that could be detrimental to the car.

Don't we use viscous LSD's with self-contained viscous fluid regardless????

The center and rear are viscous and are sealed.

[quote name='rao']That only matters if the front differential is a clutch type or cone type limited slip and the Legacy has an open front diff. Whatever you choose, make sure you use something that is rated for limited slip otherwise your syncros on't work properly. The ONLY benefit you can expect from synthetic tranny fluid is easier shifting in very cold weather during the first few minutes of operation.[/QUOTE] When you live in western Canada where it gets down to -30ºC or so, cold weather operation gets pretty important. Even now I have noticed a reduction in shift feel and it's barely below 0.

I've used redline 75/90 in my civic and it was great... My tranny was whirring to the point I was SURE I needed to replace the trans. I put in the redline and literally 2k miles later the tranny was dead quite and shifted perfect... that was over 80-100k miles ago and the trans is still running strong with me beating it on a daily basis. I've since moved to the penzoil synchromesh fluid. It is just as good for 1/4th the price... the Redline is about 8-10 dollars a quart the penzoil is like 4bucks if that. I'm sure the redline is better... but the synchromesh is great too... There are also 2 types of the penzoil/GM synchromesh fluids... one is "friction modified" for trannys with LSD's... the other is the standard one for transmissions with a dif and gears in one case... I'm not sure what I'm going to switch to... probobly Redline since it doesn't need to be replaced very often and it is a rediculously good product. Might do it this weekend.

Anyone have experience with Silkolene Silktran Syn5 in cold weather, say 0 degF to 20 degF? The original fill of Subaru gear oil does not seem to work well at that temperature, as evidenced by a reluctance to slide into 1st and 2nd gear.

[quote name='outahere']Anyone have experience with Silkolene Silktran Syn5 in cold weather, say 0 degF to 20 degF? The original fill of Subaru gear oil does not seem to work well at that temperature, as evidenced by a reluctance to slide into 1st and 2nd gear.[/QUOTE] I do not have any 1st hand experience with it, but I have tried numerous gear oils, from dino to synthetics, and I can tell you from my experiences, that this Silkolene will be pretty thick when in that cold a temp. If you are in a cooler climate year round, you should choose a thinner oil, whereas if your in a warmer climate then go a little heavier. Personally I am currently running Specialty Formulations Inc MTL-R oil, and let me say this, so far it is the BEST fluid I have come across so far. It was specifically engineered for manual transaxles, like we have. It also is solely a Grp IV & V synthetic oil makeup. Meaning it a REAL synthetic, 100%! I do not work for them nor am I compensated in any way, but when I try a product that I really like, I like to let others know, so that they can have relative confidence in selecting a tried/proven product! I live in NJ, so our climate is varied, but it pretty much doesn't go below 5 degrees, and not higher than 93 degrees, so the oil I picked is a very good match. If however you live in a colder climate, I would recommend a bit lighter oil like MTL-P, which is a 75w-85, but is also GL5 rated. I don't know of any other synth oils, that are GL5 rated. If you live in a warmer climate, like the southern states, then I would highly suggest using the Silkolene, as it is a thicker oil, better able to withstand high temps. And last if you don't want to spend the money on these premium oils, I have had a very good experience with QS & Pennzoil synthetic 75W-90 oils. The only thing about them was that they were not specifically designed for transmissions, but they do shift pretty nicely, a fair amount better than stock fluid, and you can get them almost anywhere for about $6-9 a qrt. PS: All of the oils, except the Silkolene, I have personally used in my LGT! (Actually I also tried Valvoline dino 75W-90, but found it to be no better than stock! It was cheap though at $4 p/qt.) I used them for at least 5k miles or more, so I truly am speaking from experience specific to our cars.

[quote name='edmundu']I do not have any 1st hand experience with it, but I have tried numerous gear oils, from dino to synthetics, and I can tell you from my experiences, that this Silkolene will be pretty thick when in that cold a temp. If you are in a cooler climate year round, you should choose a thinner oil, whereas if your in a warmer climate then go a little heavier. Personally I am currently running Specialty Formulations Inc MTL-R oil, and let me say this, so far it is the BEST fluid I have come across so far. It was specifically engineered for manual transaxles, like we have. It also is solely a Grp IV & V synthetic oil makeup. Meaning it a REAL synthetic, 100%! I do not work for them nor am I compensated in any way, but when I try a product that I really like, I like to let others know, so that they can have relative confidence in selecting a tried/proven product! I live in NJ, so our climate is varied, but it pretty much doesn't go below 5 degrees, and not higher than 93 degrees, so the oil I picked is a very good match. If however you live in a colder climate, I would recommend a bit lighter oil like MTL-P, which is a 75w-85, but is also GL5 rated. I don't know of any other synth oils, that are GL5 rated. If you live in a warmer climate, like the southern states, then I would highly suggest using the Silkolene, as it is a thicker oil, better able to withstand high temps. And last if you don't want to spend the money on these premium oils, I have had a very good experience with QS & Pennzoil synthetic 75W-90 oils. The only thing about them was that they were not specifically designed for transmissions, but they do shift pretty nicely, a fair amount better than stock fluid, and you can get them almost anywhere for about $6-9 a qrt. PS: All of the oils, except the Silkolene, I have personally used in my LGT! (Actually I also tried Valvoline dino 75W-90, but found it to be no better than stock! It was cheap though at $4 p/qt.) I used them for at least 5k miles or more, so I truly am speaking from experience specific to our cars.[/QUOTE] Thanks for the info on the Silkolene. It will be interesting to see how the MTL-R works out for you long term, especially next winter. I did notice that the proprieter of Specialty Formulations posts regularly to the forums at bobistheoilguy. As for the Valvoline being no better than stock, this is not surprising, as the OEM fill is allegedly Valvoline. What specifically do you like about the MTL-R? What benefits have you experienced with it in your car?

The first thing I immediately noticed was the eerily smooth engagements of the gears! I mean almost Honda like, it was that smooth! It takes very little time, about 1mi before I can downshift into 1st from a slow roll. With any of the others, it took at least 3-5 miles or longer. When trying to downshift into 2nd gear, when cold(trans not air temp) from 3rd to make a turn I would sometimes need to slow down to like 5 mph in order for it to engage, whereas with the SF fluid, I can do that without issue. When shifting between any gears, they all feel smooth and have that cushion/damped feeling. Envoking any downshift is so smooth, that you start to think that you haven't engaged the gear! I'm trying not to sound like a spokesperson, but I cannot help it! Yes, Molakule is his scr name, over there, and if you were to take a look at any reviews of his oils, you would see a pattern emerge, and it is nothing but positive! These oils are designed around performance, and not cost! And let me tell you it shows! MTL-R, has a lower viscosity number when cold, which means it will perform better than the QS & PEnnzoil I had used during winter, which were pretty good!

after having used it in two subarus i will never use 75w90ns in a subaru transmission the "ns" part means no slip thus the syncros don't slip like they are supposed and wear out - quickly from genuine experience [b]do not use redline 75w90ns in a subaru transmission[/b]

[quote name='Jaxx']after having used it in two subarus i will never use 75w90ns in a subaru transmission the "ns" part means no slip thus the syncros don't slip like they are supposed and wear out - quickly from genuine experience [b]do not use redline 75w90ns in a subaru transmission[/b][/QUOTE] While I won't question your empirical experience, your reasoning is completely wrong. Redline 75w90ns has NO friction modifiers, and is much better suited to use in a gearbox, than the regular 75w90, which is friction modified. Friction modifiers make an oil more slippery, which helps prevent chatter in a limited slip diff, but is not good for a synchronized transmission. Here is Redline's description of the 75w90ns: "This GL-5-type geal oil doesn't contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting. Can also be used in racing limited-slip differentials where weak spring design causes too much wheel spin."

[quote name='edmundu']The first thing I immediately noticed was the eerily smooth engagements of the gears! I mean almost Honda like, it was that smooth! It takes very little time, about 1mi before I can downshift into 1st from a slow roll. With any of the others, it took at least 3-5 miles or longer. When trying to downshift into 2nd gear, when cold(trans not air temp) from 3rd to make a turn I would sometimes need to slow down to like 5 mph in order for it to engage, whereas with the SF fluid, I can do that without issue. When shifting between any gears, they all feel smooth and have that cushion/damped feeling. Envoking any downshift is so smooth, that you start to think that you haven't engaged the gear! I'm trying not to sound like a spokesperson, but I cannot help it! Yes, Molakule is his scr name, over there, and if you were to take a look at any reviews of his oils, you would see a pattern emerge, and it is nothing but positive! These oils are designed around performance, and not cost! And let me tell you it shows! MTL-R, has a lower viscosity number when cold, which means it will perform better than the QS & PEnnzoil I had used during winter, which were pretty good![/QUOTE] Is it also easier to engage reverse gear?

[quote name='edmundu']........ If however you live in a colder climate, I would recommend a bit lighter oil like MTL-P, which is a 75w-85, but is also GL5 rated. I don't know of any other synth oils, that are GL5 rated..........[/QUOTE] I took a look at the SF website, and at the description of the MTL-P gear oil, and they warn not to use it with hypoid gears, which rules it out for use in the Subaru transmission. An unexpected warning, given its GL5 rating.

[quote name='outahere']I took a look at the SF website, and at the description of the MTL-P gear oil, and they warn not to use it with hypoid gears, which rules it out for use in the Subaru transmission. An unexpected warning, given its GL5 rating.[/QUOTE] Well, from conversations with "Molakule", it is NOT recommended for use in "final-drive hypoid-type differentials", meaning rear diffs or independantly filled front diffs. Our transaxle setup, although technically has a hypoid diff, is not what his website is referring to. Furthermore, he did have the fluids recently updated to include additional EP/AW additives to meet GL5 specs, so I would email him to confirm, as his website isn't always up to date. As for reverse, I have not noticed reverse being noteably better in engagement. I do not think there is any improvement to be had as this is a non-synchronised gear, so sometimes the teeth will need a little help to line up, aka roll a couple inches, go into 1st, then into reverse....etc...

[quote name='edmundu']Well, from conversations with "Molakule", it is NOT recommended for use in "final-drive hypoid-type differentials", meaning rear diffs or independantly filled front diffs. Our transaxle setup, although technically has a hypoid diff, is not what his website is referring to.........[/QUOTE] It does not make sense that this lube would be OK for use with a hypoid gear set located in a transmission case, but not OK for the same hypoid gear set located in a differential case.

Doesn't Cobb recomend using redline 75-90? [url]http://cobbtuning.com/legacy/drivetrain2.html#gearoil[/url] yup they do... matter of fact it's in their tech section too... Read for yourselves and decide... [url]http://www.cobbtuning.com/tech/gearoil/index.html[/url]

This thread (and the other floating around) [b]ROCKS[/b]. I'd never given much though to relative differences between transmission oils (or to transmission oils in general, for that matter). That said, I'm interested in trying the SF MTL-R and thought I'd order it. I don't know off hand what the capacity of the transaxle is, and my manual is sitting at home. If someone can supply that info, that'd be great. Thanks.

[quote name='Unilat']This thread (and the other floating around) [b]ROCKS[/b]. I'd never given much though to relative differences between transmission oils (or to transmission oils in general, for that matter). That said, I'm interested in trying the SF MTL-R and thought I'd order it. I don't know off hand what the capacity of the transaxle is, and my manual is sitting at home. If someone can supply that info, that'd be great. Thanks.[/QUOTE] The transaxle holds 3.7 qts, and the rear diff holds 0.8 qts. I only was able to get 3.5 or so back in, as it is tough to drain every last drop! I have the MTL-R & HDS-5 in my trans & diff! They are awesome fluids! Just order a gallon of the MTL-R, it's cheaper that way, and a qt of HDS-5 if you are also changing the diff.