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Change To Syn Gear Oil Now!

73K views 268 replies 95 participants last post by  markthomas1969 
#1 ·
Lots of people mention the subject, but maybe it needs it's own thread.

Change your gear oil to synthetic as soon as you can. I used Mobil 1. One gentleman (he inspired me) used Redline. It might be better but its hard to find, here.

Keep the car level (no ramps, you can reach the drain) and drain every drop of the old oil. Mine only has a few K miles on it. Since my car is lowered, I needed my skinny son to get at the drain plug. Don't lose the washer!

You'll need a long a$$ funnel. Then dump in that Mobil 1.

I think the owners' manual is wrong in the capacity. It calls for 3.75 quarts. I used 4.

Then go for a drive and be prepared for a seriously dramatic change in your shifting and transmission behavior. It's hard to believe it's the same machine.

Go figure.

:) :)
 
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#52 ·
Excess gear oil removal

MisterX said:
Jim,

After a day or two of running, I rechecked the level and it was 1/4 qt. high. I took the Mitey Vac and removed the excess.

Russ
I had the same problem. After I let my tranny drain for an hour and re-filled with 3.7 qts, I drove it for a 10 miles or so and let it sit overnight. When I checked it the next morning and it was over "Full". I opened the drain plug and drained about 1/4 quart out and it is now just below "F".
 
#54 ·
Wheels said:
Well I changed mine last week.

And not good.

I mixed 50/50 between redline 75w90 and 75w90ns

Now I have an issue with grinding when going into 1st from 2nd. Or from Idel. Im dropping the fluid tomorrow and putting in 75w90ns only to see how it goes from there.
Give Motul 300 a shot, it is working like a dream. I was forewarned about using Redline gear oil in our trannys (and I'm a hardcore Redline user). :)
 
#55 ·
Man where was this thread 10K mi. ago. I had the 2nd-1st shifting problems when the car was new, but noticed it got noticably WORSE when I changed my tranny fluid to 50/50 of Redline 75/90 and MTF. This blend was PERFECT for my last car, and saved a bad syncro for many miles. I'm at 20K mi. now and the damn thing grinds when sitting still going from Neutral to 1st sometimes even! I think I'm gonna try to switch up again. Where can I find this new Redline "shockproof"? I havn't seen it before...

-Jason
 
#56 · (Edited)
I actually found mine at a local motorcycle store. You might try that where you live. It's great stuff for 2-stroke dirt bike trannys.

Subaruparts.com has it. Cobb says to use the Superlight (they have three weights - superlight, light, and, er, Heavy I guess) and that works well in my car, but I never did have problems. My buddy had 2-3 grinding in his 2.2L Wagon and the Lighttweight Shockproof fixed it.

C
 
#57 ·
I talked to a Subaru Tech in Oakland the other day, and mentioned this to him. He says he's seeing a lot of these problems because everyone is switching over to synthetic. He said that the synthetics seem to be too thin to make the 1st gear syncro work well. He said that all the gears have 1 syncro between them with the exception of 1st-2nd, which has a "triple-syncro" in it, and this different syncro is why 1st is the only gear that's troublesome. He suggested that I drain out my Redline, (which I'm gonna ditch anyway at this point) and put plain old 80-90 in it. If I'm not mistaken, doesn't the manual call for 75-90, not 80-90? Did he tell me to get the thicker oil because of this problem in particular?

This weekend, I went and bought Castrol 80-90 "non-synth". My hand was shaking as I went to pay, I could hardly bring myself to buy a fluid that wasn't synthetic. I'll change out next weekend (hopefully) and see how well that does...

-Jason
 
#59 ·
I'm going to add more crap into the mix & put in my reccomendation for transaxle lube : Goodwrench Synchromesh Transaxle Lubricant. Yah it's the stuff you can buy at the local Chebby dealer.

I came upon this stuff a few years ago while I was working on Porsche 911 race cars. (my old job). We had been using Swepco & RedLine transaxle lubes on the 901 & 915 transaxles going in customer cars & our own cars. We were still experiencing what we thought was unacceptable synchro crashing due to over slipperyness. Basically the sychronizers would behave as thought they were worn out, grinding etc, long before they were measureably worn.

This phenomenon, which is well explained at the link to Cobb in a previous post, is caused by the slipperyness of the oil. Synchros are like miniature clutches, or more appropriately, brakes. They require a modicum of friction in order to do their job. The added lubricity of the sythetic based mtl lube was too high, the "brakes" were too slippery.

Again, we were using lubricants designed specifically for our application: Manual transaxles. Not plain old synthetic gear oil. Synchro crash was still an issue.

I was complaining to a friend about this one day at the dirt track. He was a GM mechanic & late model sportsman class owner/driver. He asked me if I had ever tried GM's transaxle lube & I told him I'd never heard of it. Seems that when GM introduced the Quad4 engine, the manual transmissions in the Pontiac Grand Prix's were fragging transmissions left & right. GM had engineered atf as the lubricant in their new-from-the-ground-up transaxle & it was being "crushed" by the torque that the 195hp quad4 was generating.

GM experimented with the same aftermarket fluids I had been using, redline & swepco. Their transaxles stopped exploding immediately, but they (GM) noticed the same problems I was having, synchros not working after a while, especially if you beat on the tranny.

They either comissioned or made their own lube to solve the problem. It seemed to do the trick. Thin enough to reach all the components that needed it, crush-resistant enough to maintain its hydrodynamic wedge between gears & just slippery enough to do its job with out making the synchros greasy.

I had a customer's '83 911 in the shop for some maintenance & decided to give it a try. (with his permission) He club raced 10 times a year & had about 25 races on a tranny rebuild & was beginning to crunch in 2nd gear. His tranny was in great shape other than this & had been slated for for a teardown & synchro refresh in another 2 months. I drained out the swepco & poured in the Goodwrench stuff.

He called me 2 months later to cancel the trans overhaul. He said his tranny shifted better than than it ever had. that was all the impetus I needed to drain the Redline out of my '72 911 & the boss's '76 914. Almost instant night & day difference. I was rdy to pull the tranny in the bosses car & put 1-3 synchros in it & I cancelled my plans. My decrepit trans had practically NO 1-2 synchro action & for the first time I was able to change gears without rev-matching. Not cured in the case of my car, it was still pretty worn out, but it made a big difference.

They still use it at that garage, 7 years later. Everyone that has switched to it that I know still uses it. Put it in my old Mazda 626GT & it worked great. Same with my previous hot-rod, a Peugeot 405mi16. Same with my old pedestrian '88 dl wagon.

BIG CAVEAT HERE!!

Subaru uses 75w90 oil in their transaxles. They werent originally designed to use such a light oil. Neither was Porsche for that matter though, they specified 90w. The transmissions were noticeably (though not arguably) noisier with the Goodwrench lube. Definitely more gear whine. I'd perhaps suggest those of you who are considering a trans rebuild to solve shifting problems give it a try. Those with minor complaints like balky shifting or minor grinding consider it.

all imho of course,

j.p.

silver '03 wagon (only 2 months & I have placed my order for an sti)
 
#61 ·
I think I'm going to try some of the Synchromesh. I replaced my Royal Purple over the weekend with Valvoline 80w/90, although there is some improvement in the synchros grinding I'm still getting some when shifting into 5th. The 80w/90 feels like molasses when the tranny is cold.
 
#62 ·
I'm going to buy some of this GM stuff and give it a try. What weight oil would you suggest then? Also have you put it in your 03 yet?

balkamp said:
I'm going to add more crap into the mix & put in my reccomendation for transaxle lube : Goodwrench Synchromesh Transaxle Lubricant. Yah it's the stuff you can buy at the local Chebby dealer.

I came upon this stuff a few years ago while I was working on Porsche 911 race cars. (my old job). We had been using Swepco & RedLine transaxle lubes on the 901 & 915 transaxles going in customer cars & our own cars. We were still experiencing what we thought was unacceptable synchro crashing due to over slipperyness. Basically the sychronizers would behave as thought they were worn out, grinding etc, long before they were measureably worn.

This phenomenon, which is well explained at the link to Cobb in a previous post, is caused by the slipperyness of the oil. Synchros are like miniature clutches, or more appropriately, brakes. They require a modicum of friction in order to do their job. The added lubricity of the sythetic based mtl lube was too high, the "brakes" were too slippery.

Again, we were using lubricants designed specifically for our application: Manual transaxles. Not plain old synthetic gear oil. Synchro crash was still an issue.

I was complaining to a friend about this one day at the dirt track. He was a GM mechanic & late model sportsman class owner/driver. He asked me if I had ever tried GM's transaxle lube & I told him I'd never heard of it. Seems that when GM introduced the Quad4 engine, the manual transmissions in the Pontiac Grand Prix's were fragging transmissions left & right. GM had engineered atf as the lubricant in their new-from-the-ground-up transaxle & it was being "crushed" by the torque that the 195hp quad4 was generating.

GM experimented with the same aftermarket fluids I had been using, redline & swepco. Their transaxles stopped exploding immediately, but they (GM) noticed the same problems I was having, synchros not working after a while, especially if you beat on the tranny.

They either comissioned or made their own lube to solve the problem. It seemed to do the trick. Thin enough to reach all the components that needed it, crush-resistant enough to maintain its hydrodynamic wedge between gears & just slippery enough to do its job with out making the synchros greasy.

I had a customer's '83 911 in the shop for some maintenance & decided to give it a try. (with his permission) He club raced 10 times a year & had about 25 races on a tranny rebuild & was beginning to crunch in 2nd gear. His tranny was in great shape other than this & had been slated for for a teardown & synchro refresh in another 2 months. I drained out the swepco & poured in the Goodwrench stuff.

He called me 2 months later to cancel the trans overhaul. He said his tranny shifted better than than it ever had. that was all the impetus I needed to drain the Redline out of my '72 911 & the boss's '76 914. Almost instant night & day difference. I was rdy to pull the tranny in the bosses car & put 1-3 synchros in it & I cancelled my plans. My decrepit trans had practically NO 1-2 synchro action & for the first time I was able to change gears without rev-matching. Not cured in the case of my car, it was still pretty worn out, but it made a big difference.

They still use it at that garage, 7 years later. Everyone that has switched to it that I know still uses it. Put it in my old Mazda 626GT & it worked great. Same with my previous hot-rod, a Peugeot 405mi16. Same with my old pedestrian '88 dl wagon.

BIG CAVEAT HERE!!

Subaru uses 75w90 oil in their transaxles. They werent originally designed to use such a light oil. Neither was Porsche for that matter though, they specified 90w. The transmissions were noticeably (though not arguably) noisier with the Goodwrench lube. Definitely more gear whine. I'd perhaps suggest those of you who are considering a trans rebuild to solve shifting problems give it a try. Those with minor complaints like balky shifting or minor grinding consider it.

all imho of course,

j.p.

silver '03 wagon (only 2 months & I have placed my order for an sti)
 
#63 ·
There aren't any optional weights. It's relatively thin, pours about like room temp 30weight.

Don't have in my car for one big reason: Mine's an automatic :p

Did use it in my '88 wagon though, same basic transaxle design.

I'd say if you HAVE a shifting problem, try it. If you are content with how your car changes gears, nm it. It's like 7.95 a qt so a bit cheaper than you can find Redline at most places.

It sure isn't going to hurt anything.

Anybody who tries, post results here. I'm confident you'll notice a difference after a few days driving as it works its way in.

Why the auto? I'm old & lame & this fugging car seems to have revitalized me to the point where I kick myself for getting the auto :/

j.p.

silver '03 wagon
 
#64 ·
I just put some of the Synchromesh in over the weekend. I had been having problems with shifts in cold weather. Especially in the morning, the tranny was really really stiff for the first 15 minutes of driving. Also, downshifts were rather hard even with rev matching. Well, this morning at about 0 degrees the tranny was not stiff at all. I also notice better downshifting. I do feel more notchyness, however. No regrets so far.
 
#65 ·
I switched to the Synchromesh last Friday. This is the 4th type of tranny fluid that I've tried (OEM, Royal Purple 75w/90, Valvoline 80w/90). The Valvoline 80w/90 definitely improved shifts into fourth but I was still getting the grinding when I shifted into fifth at high rpms, also the 80w/90 felt like molasses in the gear box, especially when cold. So far the Synchromesh seems good, upshifts are more effortless and downshifts seems to slide into gear easier. I also notice that I am able to downshift into first much easier when approaching a stop, before I almost had to be at a standstill before the car would go into first gear. I've been giving the fluid a chance to get worked in to all the nooks and crannys of the tranny and I haven't really tested it on the fifth gear/high rep shift yet. I'll give more feedback once I drive with it in for awhile. By the way, I paid $9.91/quart at the chevy dealer. If it helps it will definitely be worth the price.
 
#67 ·
No problem at all j.p. Thank you for pointing out the Synchromesh to us. I don't want to take my car to the dealer and have them tell me that they are not going to cover my synchro problem because of my mods so I figured I would experiment with different fluids to see if that would correct/improve the problem. Yes, $9.91 retail (Autoway Chevy in Tampa).
 
#71 ·
I think I am going to give the Motul 300 a shot in my tranny, seems all the major Subaru teams are using it so it should be good.

And I think their 300V 10W-40 engine oil would be good for the hot summers too.

So it looks like I will give all the motul stuff a shot the next time I am under my car for an oil change. What type of oil should I put in the rear diff, any thoughts on that?
 
#73 ·
Motul 300 rocks

I have over 2K miles with Motul 300 in my tranny and it works super, bearing whine is considerably better and no longer embarrasing. The shifting is great (for a 5spd Subie trans) with no grinding or other issues at all.

I have also religiously used Redline engine oil in my cars for the last 10 years (with one departure to Mobil 1 for my PT, a cheaper, less important car) with great results.
 
#76 ·
Changed to Mobil1 last night. It does seem to shift smoother, especially down-shifts. That plus the new Momo Race Air Leather shift knob are GREAT!!! WOOHOO

Btw, there was a coating of metal on the magnet in the drain plug. But nothing excessive and no big chips.

Leo
 
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