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{{Official Trans Fluid Thread}}

14K views 47 replies 30 participants last post by  rotorocker 
#1 · (Edited)
{{Official Trans Fluid Thread}} - Post experiences only!!

I've seen a bunch of trans fluid threads floating around (read many of them) and I'd like to have a single spot for members to share their ideas on what worked and what didn't. Please list what you've tried and the results in the format below. Be as descriptive as possible.

Things I've tried:
1. Mobil 1
2. Amsoil
3. Redline

Results:
1. I changed to Mobil 1 from the stock fluid at about 16k a year ago. It felt to me that the ease of shifting was improved. I kept the fluid in the car for about a year and 15k miles. I had no problems during this period. The shifting was never "steller" but offered an improvement over stock.

2. I changed to Amsoil from the Mobil one above about two weeks ago. I immediately noticed that the transmission would take longer to go into gear between shifts. I now have to be VERY ginger with the shift into first or the syncro will grind. I have less than 1k miles on this oil and it needs to go in the worst way.

3. I mixed 2 Q of Redline Lightweight Shockproof with ~1.7 Q of Redline 75W-90NS Gear Oil. I've had this oil for about one week. In that time the shifting is noticeably improved. Overall it doesn't feel much different than the Mobil 1. I will update this the longer I have the fluid in the trans.
 
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#2 · (Edited)
I mixed up a batch of "Uncle Scottys Cocktail" but a full synthetic version in my 06 TR at 15k miles.

1 qt Redline lightweight shockproof
1 qt Amsoil syncromesh
2 qt Amsoil 75w90 gear oil.

NOTE: 5MT CAPACITY IS 3.8 QTS USE GEAR OIL AS TOP OFF FLUID. DO NOT DUMP IN ALL 4 QTS. PUT IN 3.25 AND CHECK ETC.

I have been using it for 10,000 miles and it works 10x better than stock. Took away the notchiness of the shifts, engages smoother etc. Note: 06 5MT tranny's shift slightly better from factory than the 02-05 5mt due to a slight redesign. Therefore the change wasn't as drastic as it was in the 02 below.


Also mixed the normal "Uncle Scottys Cocktail" from Nasioc and put it in an 02 bugeye 5MT at 40k miles.

Previously it had been filled with fresh Valvoline 75w90 gear oil. Shifting with Valvoline was awful, first gear ground every time on the 2-1 shift and reverse felt impossible to find.

So we put in USC which is:

1 qt Syncormesh fluid (pennsoil, gm or amsoil)
1 qt redline lightweight shockproof
2 qt castrol Hypoy C 80w 90 gear oil.

NOTE: 5MT CAPACITY IS 3.8 QTS USE GEAR OIL AS TOP OFF FLUID. DO NOT DUMP IN ALL 4 QTS. PUT IN 3.25 AND CHECK ETC.

Worked amazing. Felt like a miracle cure. First gear shifted up and down like it was double syncroed, reverse was easy to find consistantly, and shifting was way smoother. I highly recommend it on 02-05 5MT's. Been using for 3-5 k miles now with no decrease in performance.

Vendors for USC:

Togg's

http://www.tognottisautoworld.com/default.aspx?AspxAutoDetectCookieSupport=1

They have everything to make a full syn version, and carry Most major brands of synthetics for you die hard M1, Redline, Royal Purpal, Kendall, Castrol, Valvoline, Amsoil, etc. SYNTHETIC fans.

Pepboy's sells the Castrol Hypoy C as well as the Pennzoil Syncromesh.

www.amazon.com also sells the ingrediants.

Also check your local vendors.
 
#12 ·
I mixed up a batch of "Uncle Scottys Cocktail" but a full synthetic version in my 06 TR at 15k miles.

1 qt Redline lightweight shockproof
1 qt Amsoil syncromesh
2 qt Amsoil 75w90 gear oil.

NOTE: 5MT CAPACITY IS 3.8 QTS USE GEAR OIL AS TOP OFF FLUID. DO NOT DUMP IN ALL 4 QTS. PUT IN 3.25 AND CHECK ETC.

I have been using it for 3,000 miles and it works 10x better than stock. Took away the nothciness of the shifts, engages smoother etc. Note: 06 5MT tranny's shift slightly better from factory than the 02-05 5mt due to a slight redesign. Therefore the change wasn't as drastic as it was in the 02 below.


Also mixed the normal "Uncle Scottys Cocktail" from Nasioc and put it in an 02 bugeye 5MT at 40k miles.

Previously it had been filled with fresh Valvoline 75w90 gear oil. Shifting with Valvoline was awful, first gear ground every time on the 2-1 shift and reverse felt impossible to find.

So we put in USC which is:

1 qt Syncormesh fluid (pennsoil, gm or amsoil)
1 qt redline lightweight shockproof
2 qt castrol Hypoy C 80w 90 gear oil.

NOTE: 5MT CAPACITY IS 3.8 QTS USE GEAR OIL AS TOP OFF FLUID. DO NOT DUMP IN ALL 4 QTS. PUT IN 3.25 AND CHECK ETC.

Worked amazing. Felt like a miracle cure. First gear shifted up and down like it was double syncroed, reverse was easy to find consistantly, and shifting was way smoother. I highly recommend it on 02-05 5MT's. Been using for 3-5 k miles now with no decrease in performance.

Vendors for USC:

Togg's

http://www.tognottisautoworld.com/default.aspx?AspxAutoDetectCookieSupport=1

They have everything to make a full syn version, and carry Most major brands of synthetics for you die hard M1, Redline, Royal Purpal, Kendall, Castrol, Valvoline, Amsoil, etc. SYNTHETIC fans.

Pepboy's sells the Castrol Hypoy C as well as the Pennzoil Syncromesh.

www.amazon.com also sells the ingrediants.

Also check your local vendors.
hmmm i dont get it, which mix is better?
sorry im a noob
thanks
 
#3 ·

Things I've tried:
1. Mobil 1

Results:
1. I changed to Mobil 1 from the stock fluid at about 16k a year ago. It felt to me that the ease of shifting was improved. I kept the fluid in the car for about a year and 15k miles. I had no problems during this period. The shifting was never "steller" but offered an improvement over stock.
I am running Mobil 1 also. I agree with your description. Not great...but better than stock.

I still get first gear grinding if I am not careful.

Later,
Patrick
 
#9 ·
I am running Mobil 1 also. I agree with your description. Not great...but better than stock. I still get first gear grinding if I am not careful.
+1. I'm doing my 60K service this week & am planning on using USC. Does anyone know where to get Redline Lightweight Shockproof locally? Or is it only available online?
 
#5 ·
My experiences.

1: I switched from stock to Mobil-1 to help a slightly lazy 1st gear synchro.

Result - Better at first, then progressively worse.

2: I then switched to Redline.

Result - No improvement whatsoever.

3: I then switched to Amsoil.

Result - No improvement whatsoever.

4: Back to good 'ol Valvoline.

Result - Drastically improved. Right back where I started with a slightly lazy 1st gear synchro.

I'm done changing trans fluid.
 
#6 ·
I'm running the cocktail as well, and it's amazing. I had a friend (who didn't know about the change) get in and play with it a bit, he immediately said "oh, shifting is nicer! What happened here?"
 
#7 ·
+1 for Uncle Scottys Cocktail I took the forums advice and it paid off very well and makes me happy with every shift. Noted smother shifts and most of all peace of mind as I bought a used car and had no idea what god awfull stuff was in it before. You can buy the whole cocktail off an amozon vendor. Make sure you sort out the fact that its the same vendor they shiped it in to different packages charging me twice for shiping from the same caompany call and order so you get one package.:screwy: :screwy:
 
#8 ·
I'm using Royal Purple, started using it at 45k, now at 50k, seems better than dino oil.
 
#11 ·
I ended up having my local Advance Auto order it for me.

When I drained the tranny fluid, it looked like brand new oil. It had a nice golden brown color to it & still felt really thick. It didn't smell burnt at all either.

I used Uncle Scotty's Cocktail per the 2nd post here & I immediately noticed a difference. Smoother shifts with alot less effort & less resistance going from gear to gear, especially 1st & reverse. :thumbup:
 
#14 ·
I'm going to follow up post on my experiences with the Redline mixture.

2 qt. Lightweight Shockproof
~2 qt. 75W-90 Synthetic

I'm at 35k now and transmission has never felt better! The syncros actually work. 1st gear is an absolute breeze to get into, even at speeds around 20 mph. This became very useful at an autox event which had a VERY tight turn around and made a downshift handy. The transmission still is a touch "notchy", but overall I don't think I could be much happier with it.

I'm very much coming to the opinion that viscosity of the oil used has a direct relationship with how well the syncros work.
 
#17 ·
Anyone tried the Extra S from Subaru yet? Rumor a while back was that they use it in one of their race cars. It comes in a big drum from Subaru (5 gallons or something like that) for about $100 bucks. That's what I plan on putting in mine in the near future.
 
#19 ·
#21 ·
i used uncle scotty's cocktail for the trans and Mobil1 75W90 synthetic for the rear differential
 
#22 ·
putting in uncle scottys cocktail this week for my 02 tranny (everything ordered from amazon) and i used redline in my rear differential about 4 weeks ago

cant wait for the improvement of USC since my gears have been stubborn lately with the cold weather
 
#23 ·
wow!!! USC has done wonders for my 02 tranny...
before: grinding, hesitation accepting gears, forget about reverse unless you roll forward first, drove horrible with the engine cold....i really thought i was going to see the end of my transmission

after: no grinding, no hesitation, smooth between shifts, always takes the gear except 1st sometimes in a roll w/o double clutch (havnt tried w/ double clutching, probably works though), always get in reverse if the engine is warm

transmission feels brand new again...experiencing other problems now as a result of taking my IC off to get to the fill hole :( next time im using a funnel with a hose connected instead of taking the IC off
 
#26 ·
1) Stock factory fluid: no real issues. Shifted just ok.

2) At 10,570 miles I changed out the rear diff to M1 75w90 and the front/tran to USC (original formula). It's so easy to do these changes, I might just do it again at 20k (lol).

I let it drain on level ground for about 3hrs, but the initial 3.25 qts filled it right to the middle of the dipstick. After a day of driving, it still reads in the middle, so yes... make sure you don't put all 4 qts in.

1 qt Pennzoil Synchromesh (pep bys)
1 qt Redline Lt Wgt Shockproof (amazon)
1.25 qt Castol Hypro C 80w90 (pep bys)
T-70 torx bit (amazon)
Measured funnel w/ hose (pep bys)

The fill order was Syncromesh, Redline Shockproof, and Castrol, with the top-off (.25qt) being Castrol.

The verdict? I notice a very real improvement right away in all gears. Smooth as silk. Maybe say a 50% improvement?
 
#27 ·
I've got an '06 2.5i wagon, and never really had a problem with the stock fluid, shifted fine maybe a little "notchy" at times.


I changed my tranny fluid at 35k and put in USC, not because I was having problems shifting but because I'd read that its pretty good for curing "notchyness" so I figured it would be like preventative maintenence. It's holding up fine after 6k, even when I double clutch down to first smooth as butter. Reverse doesn't want to slide in sometimes on the first start, have to let it roll back about and inch then no problem. I'm thinkin of trying just the redline combo next time, maybe at 45k if I have some extra money.
 
#28 ·
cobb used to have a good fluid type comparison on their website but now i cannot find it. but judging by some of the posts here it would be valuable - for instance some fluids have additives that are easy on your syncros but wear your bearings more, and vice-versa.

so thats to say that if you use a fluid that makes your syncros fly real smooth, you could be doing long term damage to your bearings; couple of people mentioned using race fluid and my first thought is that race cars are meant to perform but are not meant to last any longer than they have to...
 
#29 ·
for instance some fluids have additives that are easy on your syncros but wear your bearings more, and vice-versa.

so thats to say that if you use a fluid that makes your syncros fly real smooth, you could be doing long term damage to your bearings
Interesting. Does anyone know anything more about this?
 
#32 · (Edited)
I used USC in the 5sp with plain old redline 75w-90 in the rear end.

Worked like a charm. I could get the tranny to go into first gear from 30 mph without much force.
however...i no longer have that first gear. but that's probably from launching 200 times...

Now that I've got the 6sp I'm going to go 100% OEM until I learn more about what can go in the limited slip.
 
#37 · (Edited)
I tried Castrol Syntec 75W90 in the box at my first gearbox oil change, and I hated it. Got grinding when shifting from 3rd to 4th at >4500 rpm.

So I went looking around for the ingredients for Uncle Scotty's Cocktail. However, I couldn't find all the components locally, so I made a substitution as follows:

1 qt Redline SuperLight Shockproof (as opposed to Lightweight Shockproof)
1 qt Redline 75W90NS (to mimic the Pennzoil Synchromesh....which has no friction additives)
1.8 qt Castrol Hypoy C 80W90



(Redline water wetter not added LOL)

I am now a thorough believer in the USC gospel....'cuz the tranny feels better than ever with this mixture. I've done circa 10000km on it with no complaints thus far.
 
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