How to change manual transmission fluid

[murcod]

Just dropping in to thank Kuronekko for posting this tutorial. I used it as a guide to perform my own transmission oil change and she shifts much better. The oil change has minimised my second gear transmission rubbing noise.

I did not go the 75w90 route because Redline oils are expensive in Australia ($27 bottle). I used Castrol 75w85 mineral oil as I figured that anything would be better than the factory oil, which had done 40,000 km.

I think I've got the same issue with second gear- it just doesn't want to change as quickly / smoothly as the others. The dealer has already changed my oil once - probably to auto trans fluid or something else not so good for trans life.....

Interesting about the clutch. Did you change the fluid and bleed it? I wonder if that could have been more of a problem than the trans oil itself? (eg. If it hasn't been disengaging fully.)

[KuroNekko]

Oh, by "clutch flush" you mean a clutch fluid bleed similar to a brake bleed? I've never done one, but now I know what you are talking about.

[murcod]

Oh, by "clutch flush" you mean a clutch fluid bleed similar to a brake bleed? I've never done one, but now I know what you are talking about.

Very much the same. I've just been browsing the workshop manual and the brake fluid reservoir also supplies the clutch.

Clutch fluid is supplied from brake fluid reservoir. Clutch fluid level can be checked by brake fluid level of brake fluid reservoir.

The instructions don't say to remove anything for access (eg. air filter box) so perhaps access is easy to the bleeder nipple?

Bleeding operation is necessary to remove air whenever it entered hydraulic clutch system.
1) Fill master cylinder reservoir (1) with brake fluid and keep at least one-half full of fluid during bleeding operation.
2) Remove bleeder plug cap. Attach a vinyl tube (1) to bleeder plug, and insert the other end into container (2).
3) Depress clutch pedal several times, and then while holding it depressed, loosen bleeder plug about one-third to one-half turn.
4) When fluid pressure in cylinder is almost depleted, retighten bleeder plug.
5) Repeat this operation until there are no more air bubbles in hydraulic line.
6) When bubbles stop, depress and hold clutch pedal, and tighten bleeder plug.
Tightening torque
Clutch bleeder plug : 5.0 N·m ( 0.5 kg-m, 4.0 lbf-ft)
7) Attach bleeder plug cap.
8) After completing bleeding operation, apply fluid pressure to pipe line and check for leakage.
9) Refill master cylinder reservoir (1) with fluid up to specified level.
10) Check clutch pedal for operation. If spongy condition is felt, repeat entire procedure of bleeding.

[SamirD]

Since the clutch also uses brake fluid, I'd highly recommend using castrol srf for the brake/clutch fluid. It will probably work wonders to keep that system at optimum performance.

[murcod]

Dragging this back up....

I was looking into the manual trans oil and found this on the factory service manual:

NOTE:
It is highly recommended to use “SUZUKI GEAR OIL 75W-80”.
Transaxle oil specification
: SUZUKI GEAR OIL 99000–22B21–036
: API GL-4 (For SAE classification, refer to viscosity chart [A] in figure.)

The viscosity chart is below:

Kizashi viscosity chart.jpg (83.21 KiB) Viewed 9246 times

It shows 75W80, 75W85 and 75W90 all as suitable across the entire temperature range. I'm guessing they "highly recommend" their own 75W80 for $$$ in their pocket and also 75W80 should give better fuel economy over 75W90 (more vehicles sales at the expense of long term protection?)

I was wondering how the people who have switched to 75W90 are finding the gear changes (2nd gear in particular) in the cold climates?

PS: I tried finding further info (ie. synthetic or mineral based) on the recommended Suzuki "GEAR OIL 99000–22B21–036" but could find zilch.

[KuroNekko]

My gear shifts are decent and are an improvement over the stock fluid. However, I sometimes have difficultly shifting to 1st and Reverse. It feels like the syncro not engaging correctly. I don't have much issue with 2nd or any other gears.

The cars still makes the gear noise in 2nd gear at low RPMs but it has always done that.

I wish Suzuki made a better shifter like Mazda or Honda, but the throws are medium and not as bad as many other manuals found in lower-grade cars.

[murcod]

It all sounds good on paper:

The triple cone synchronizing mechanism is provided to 1st and 2nd gear synchromesh devices for high performance of shifting to 2nd gear in particular.

I'm thinking perhaps the thinner 75W80 synthetic would help with the 1st and reverse issues? I've never noticed those problems with the "new" fluid Suzuki put in mine, but I also live in a significantly warmer climate.

[KuroNekko]

It all sounds good on paper:

The triple cone synchronizing mechanism is provided to 1st and 2nd gear synchromesh devices for high performance of shifting to 2nd gear in particular.

I'm thinking perhaps the thinner 75W80 synthetic would help with the 1st and reverse issues? I've never noticed those problems with the "new" fluid Suzuki put in mine, but I also live in a significantly warmer climate.

Nope, they were there before the fluid change. Fluid change made everything better. I had similar reverse gear issues with my Mazda, but the Kizashi's is a bit worse. However, it's really not a problem and more annoying than anything.

[~tc~]

It all sounds good on paper:

The triple cone synchronizing mechanism is provided to 1st and 2nd gear synchromesh devices for high performance of shifting to 2nd gear in particular.

I'm thinking perhaps the thinner 75W80 synthetic would help with the 1st and reverse issues? I've never noticed those problems with the "new" fluid Suzuki put in mine, but I also live in a significantly warmer climate.

A lot of people in all kinds of cars have reported shifting issues after switching to synthetic ... It's just too slippery for the synchros to spin up. That's the point with the Redline MT series of fluids - they make sure they don't have TOO much lubricity for the synchros. Also, some oils may not be compatible with yellow metal (brass, bronze) synchros.

[murcod]

A lot of people in all kinds of cars have reported shifting issues after switching to synthetic ... It's just too slippery for the synchros to spin up. That's the point with the Redline MT series of fluids - they make sure they don't have TOO much lubricity for the synchros. Also, some oils may not be compatible with yellow metal (brass, bronze) synchros.

Yes, Redline do push that aspect. Suzuki point out the 75W80 being preferred, what I'm saying is perhaps the thinner 75W80 synthetic might work better than the 75W90 synthetic. Usually, with shift problems, mechanical workshops will fill the trans with a lower viscosity oil- sometimes even ATF.

The GL4 rating spec covers the brass/ bronze issue - it was covered a lot earlier on in the thread. Redline GL5 is also brass/ bronze friendly- most other brands aren't.

(KuroNekko could even have clutch issues like how an earlier person reported an improvement after bleeding.)