How to check trans oil level? Additives any good?

[Rusteee]

Hi there
Just a bit suspect about my box, its a 6speed LSD from a BZR trueno. No matter how soft I drive it (especially when its cold), I always get a nick or crunch from the syncros mainly in 3rd 4th and 5th, plus 4th feels a bit rough. Is there any way to actually check the oil level in the box? Also I've seen a few threads on additives but seems theres a few to choose from, has anyone got any recomendations of what they have found to work well for this type of thing?.
Cheers

[Adoom]

Normally the speedo drive gear is the dip stick on a fwd box. Undo the bolt where the speedo cable goes into the box, the whole thing should come out with the drive gear attached. Don't worry nothing can fall off. If the oil level can be seen on the gear that should mean its full.

I have no experience with these boxes but I am pretty sure this is how you check the level.
Can't help with additives though.

[Bling]

I thought the level was determined by the filler hole on the front... or was it back I can't remember.

But from what I recall, its full when it starts to pour out of the filler hole. Do a search though as its been covered I just can't remember the exact procedure.

[xsspeed]

I thought the level was determined by the filler hole on the front... or was it back I can't remember.

But from what I recall, its full when it starts to pour out of the filler hole. Do a search though as its been covered I just can't remember the exact procedure.

+1 but have no idea if this is different for the 6spd

as for additives, redline shockproof seems to be the recomended route, though never used it. Search shockproof it will come up.

Also box could have chipped teeth. The 6spds arent exactly reknown for their strength

[rollaholic]

yeah have a search im sure you will find sergei complaining about destroying 6 speeds with normal driving

[Mr Revhead]

its the bung at the front you use, level should be up to that

3rd syncro on those is common to wear, but 4th and 5th etc isnt
i would check the level, if its very low, top it up
if its not, i would change the oil.
is the crown wheel thats weak on thes

[Rusteee]

Oh good s**t, cheers for that ay. I hope its not chipped teeth lol the car has only been in nz for 2 years and by the looks of it had a bloody good owner before me. But I spose you never know...
Where abouts is that bung sorry? I've only ever done little mazda gearboxs and it was all drain out the bottom and fill through speedo cable hole.

[Mr Revhead]

front of the gear box, about half way up. 24mm easy to spot. is it 24? been a while pretty sure it is

[levinguy]

i thought the redline shockproof was a complete gearbox oil, not an additive? also i think its the same way as mentioned, undo the plug half way up, usually a 24mm bolt half way up, undo, and check the level.

[Rusteee]

Oh mint, thanks for that. Yeah I thought it could be that but wanted to make sure before i done anything. I checked the service manual and stuff but they didnt even state it in there mind you I spose its pretty obvious

[xsspeed]

24mm sounds right

and yeah shockproof i think is a full oil/never used it though

[cat007]

what happens if you over-fill a gearbox? I guess it just causes un-needed drag?

[xsspeed]

assuming you fill it in the side hole you will probably have trouble overfilling it, as when it gets up to the correct level it will start leaking back out the hole you are trying to fill it in.

[cat007]

assuming you fill it in the side hole you will probably have trouble overfilling it, as when it gets up to the correct level it will start leaking back out the hole you are trying to fill it in.

What about for us north/south rwd folk where its easier to fill from the gearstick whole

I'm aware that again you'd take out the drain hole in the side so technically you cant over-fill - but if you left that in, what would happen if you did over-fill?

[xsspeed]

haha fail, all I had was a fwd gbox in my head lol

I guess yeah as you said more friction in the box.

If you have a workshop manual (for the original car your gbox was from) they typically tell you how many litres of oil you need. Failing that I am sure it will be on the enets somewhere (reliable or not?)

I would be more inclined to measure first rather than judge how much you have used by whats coming out the hole.

[Mr Revhead]

toyota RWD boxes are filled by the same method, 24mm bung in the side.
but yeah can do as above if you cbf using a jack

[1I1]

Yip would be pretty hard to overfill one of these gearbox's.. unless you are filling from the wrong point

The main plug to fill up through is on the front. The drain plug is on the passenger side of the gearbox right at the bottom (bottom left side of your passenger axle).

My 6speed took 2.6L of oil (that was from completely empty)

[Heylin]

For additives I reccomend Pro-Ma MBL8. Its $35 for a bottle and you can use it in your Transmission and Engine Oil.

1 bottle will do 2 4cylinder oil changes and a couple of transmissions.

Ive used this in my MR2 for 7 years its fixed my 3rd gear syncro problems and most likely has contributed to my long engine, gearbox and previous old turbo life (lasted to 185,000 kms).

Ive used this in all my cars (Rotary Cosmo, Legacy B4, AW11 MR2, and SW20), and more recently my friend used it to fix tapping sound in his 300ZX Twin Turbo.

[ROBODISCO_20v]

An easy way around the crunching gears is to double clutch. I mangaed to kill a couple of 3rd gear syncros in my first two Corollas. Learning to drive a truck & using Castrol Syntrax 75W-90 saved my later cars

[method]

Redline MT90

"MT-90
Popular in Nissan, Toyota and Mazda manual transmissions and transaxles as well as other selected applications, this is a 75W90 GL-4 Gear Oil that’s slightly heavier than MTL. Provides excellent protection of gears and synchronizers and its balanced slipperiness provides a perfect coefficient of friction, allowing easier shifting. "

I use that in my gearbox and redline gear oil in my diff.

3ltrs will set you back about $120 but it is the best oil money can buy IMO. Price is because it is fully synthetic.