Gearbox/ Diff Oil, "98 Forester

NachaLuva

NachaLuva

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Does anyone know what gearbox oil I should use in my '98 Forester 5spd DR?

Since I got it about 6mths ago I have had big problems with it crunching gears & when its cold sometimes it refuses to go into 2nd. Even when hot it wont go into 1st unless completely stationary.

The oil is at the right level & clear (slightly yellow but clear, if you know what I mean).

I know there's all sorts of tricks you can do to help the synchro, like additives, better oil, etc. Someone somewhere mentioned red stuff...

What can I do to get the synchro working properly?

Also I will put in a diff breather sometime, & I'll do the diff oil at the same time. What should I use for that?
 
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I use multitrax in my Forester gearbox and syntrax in my Impreza
 
I'm not sure what is used in my rear diff but for the front (Gearbox/Diff Oil) I use Syntrax 75W/90 in my Forry (MY05 XT man)

Regards
Mr Turbo
 
Rally said:
I use multitrax in my Forester gearbox and syntrax in my Impreza
Click to expand...

What grade? Why the different oils?

If the synchro is worn will a lighter grade help?

& what about this thing of adding some auto fluid to the oil to help with shock resistance...or is that one of the many urban myths?
 
The Forrie runs the 5 speed dual range box and the low horsepower, so the mineral oil should suffice. The Impreza runs the 6 speed gearbox and probably twice the power and I compete in that, so I prefer the synthetic oil for the harder life the Impreza has (Impreza has launch control 6000RPM dumps, etc). Some people have found Redline (I think that is the brand) oil but I understand it is both expensive and needs more numerous changes. I think the Multitrax is only available in 80W90, and I think the Syntrax also is only available in one viscosity. I understand Subaru gearboxes require specific oils like Multitrax- I don't think you can use just any gear oil. Don't know about adding ATF- although some manuals do run it, I have not heard of it being combined.
 
I have used Syntrax ever since I swapped the gearbox over a couple of years back and then refilled with some cheap GL5 rated oil. Gear change was terrible!! Syntrax has worked well for me and although it costs a bit, not as if you change it all the time.

I do find 2nd gear a little tight to get into on cold mornings, but for me that would be around 0-5 degs in winter.
 
After much discussion & research, I've settled on Penrite SIN GEAR 75
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Its fully synthetic, 75W90 API GL5/6. A little expensive, 2x 2.5L containers cost $110, but I wont have to do it again for a while & it should help my gear changes ;)


So today I did my 1st gearbox oil change :biggrin:

Took a bit of effort to get the nut off, magnet had some filings but I dont think too bad (comments?):
img1624xc.jpg


Then cleaned. Note the magnet in the middle (very nice touch Mr.Fuji):
img1630fn.jpg

By nachaluva at 2012-01-16

I had just put through 2 cans of SUEC so the air filter assembly was already off giving me easy access to the filler/dipstick. I put in about 4L., reassembled everything & went for a spin around the block.

There is some improvement but not as much as I had been hoping for. I'll know more when I have a decent drive, esp when its cold.
 
Gidday NL

Nachaluva said:
What grade? Why the different oils?

If the synchro is worn will a lighter grade help?
Click to expand...

A synchro ring is like a small, conical clutch that spins the stationary gear up to speed as you engage the gear. The gear is actually always engaged, however the synchromesh ring has teeth around both of the two parts, one set on the synchro ring, and the other as part of the gear (three in the 2006 Forester ... apparently). When you engage the gear, the synchro ring spins the gear and the synchro ring on the input shaft up to the same speed, and then a third part (collar) slides over the two toothed circumferences, locking the two parts of the assembly together.

Of course, this only applies to constant mesh gearboxes. One is unlikely to encounter a non-constant mesh gearbox these days, except maybe in a tractor ... .

I haven't thought about it before, but it is likely that a heavier grade oil would help, rather than lighter ... As the cones get worn, one needs a higher viscosity oil to help them "grab". In a normally functioning box, the oil is largely there to keep the two parts from welding together ...

& what about this thing of adding some auto fluid to the oil to help with shock resistance...or is that one of the many urban myths?
Click to expand...

I would be willing to listen to ideas about this, but it sounds a tad strange to me ...
 
Got a guestion for you guys while we are talking about gears.

Does down or upshifting and skipping a gear cause any problems??

I.E going from 3rd to 5th or 4th to 2nd?
Or even 5th to 2nd which I do abit??

Taza
 
taza said:
Does down or upshifting and skipping a gear cause any problems??

I.E going from 3rd to 5th or 4th to 2nd?
Or even 5th to 2nd which I do abit??

Taza
Click to expand...

Only if you over rev it lol :poke:

I'd try to protect 2nd as much as you can, its always the 1st to develop problems, but if you blip the throttle as you downshift to rev match (& dont over rev lol :raspberry:) I cant see a problem
 
Gidday Taza

taza said:
Got a guestion for you guys while we are talking about gears.

Does down or upshifting and skipping a gear cause any problems??

I.E going from 3rd to 5th or 4th to 2nd?
Or even 5th to 2nd which I do abit??

Taza
Click to expand...

I have owned a couple of cars that said not to do this in the owner's manual (not Subarus).

Subi manuals say not to rest your hand on the gear lever when not changing gears. I suspect that this wears the linkages ... :(.

My 2006 2.5L N/A Fox manual tells me not to exceed 188 km/h in LO range/5th ... :lildevil:.

Doesn't say anything else about skipping from gear to gear.

I suspect it depends on both the design and strength of the box, but I don't really know this ...
 
Ratbag said:
I have owned a couple of cars that said not to do this in the owner's manual (not Subarus).

Subi manuals say not to rest your hand on the gear lever when not changing gears. I suspect that this wears the linkages ... :(.

My 2006 2.5L N/A Fox manual tells me not to exceed 188 km/h in LO range/5th ... :lildevil:.

Doesn't say anything else about skipping from gear to gear.

I suspect it depends on both the design and strength of the box, but I don't really know this ...
Click to expand...

Want to test that 188km/hr in LO Range???? haha
I reckon it would do it. I have done 195km/hr in my 2.0l N/A in high. lol
Yes Nachaluva yours will do it too :lol:
 
OK I can report back now its had some use.

It does feel better when cold & there is a marginal improvement when hot. I guess the box is just worn :( but at least this oil will do the best job of protecting it :biggrin:
 
So what oil did you end up using?

That magentic drain plug looks pretty good for the age of the vehicle, nothing to worry about there - it's when a chunk or part of a shim comes out that you should be worried!

Cheers

Bennie
 
I used Penrite SIN GEAR 75. Its fully synthetic, 75W90 API GL5/6
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Yeah I didnt think the plug was too bad
 
Sorry for the huge thread-dig here, but can anyone point me at a useful vid online (or doc to follow) to do the gearbox and diff oil changes on a 2.0L NA 5sp? I see a few around but wonder if anyone has found something especially helpful
 
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