Changing your Gearbox oil.

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tractorboy
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Re: Changing your Gearbox oil.

Post by tractorboy »

Yup, 2 quarts is all you need.

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Re: Changing your Gearbox oil.

Post by RX-8IGHT »

Hi All, here's my version of gearbox oil change without ramps or four axle stands, sounds a bit faffy but was dead straight forward and no mess.

Jack car up from passenger side, support on axle stands.
Undo and remove gearbox filling plug, discard seal.
Position oil catch container.
Undo and remove gearbox drain plug, discard seal.
Jack car up slightly and remove axle stands.
Lower car fully.
While waiting for the oil to drain clean filling and drain plugs, install new seals.
Jack car up from passenger side, support on axle stands.
Clean off any old oil deposits.
Refit drain plug and seal and torque tighten.
Insert plastic pipe down through the engine bay and into the gearbox filler hole.
Secure plastic pipe in engine bay with a cable tie to prevent it sagging or falling.
Jack car up slightly and remove axle stands.
Lower car fully.
Insert plastic pipe into oil bottle spout and seal/secure with duct tape.
Make a small breather hole in the base of the oil bottle.
Squeeze bottle to deploy oil down the pipe into the gearbox.
Change oil bottle when empty.
Keep checking the gearbox filler hole until oil dribbles out.
Jack car up from passenger side, support on axle stands.
Seal the end remove plastic pipe.
Clean off residual oil.
Refit filling plug and seal and torque tighten.
Jack car up slightly and remove axle stands.
Lower car fully.
Job done.

Cheers...
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Re: Changing your Gearbox oil.

Post by acegeezer »

Tariq wrote:Bit of a bump of a topic but where to people get their washers from?
Picking up a rex tomorrow and want to get this done next weekend.
Got mine here.. http://www.ebay.co.uk/itm/160831055655
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Re: Changing your Gearbox oil.

Post by DB2626983C »

It states that it's not compatible with the Rx8?

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Re: Changing your Gearbox oil.

Post by Joel2005+ »

Changed mine today for Redline MT90 , got to say its silky smooth , what a difference, did the diff to with Redline 75w-90.....
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Re: Changing your Gearbox oil.

Post by MJ43 »

On the 6 speed box what is the torque figure for tightening up the the drain plug and level plug?

Ok found it
http://5cats.org/rx8/trans_diff_refill/

RX-8 torque specs
transmission filler/drain bolts 27-48 N-m
differential filler/drain bolts 39.2-53.9 N-m

Hope these are ok?
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Re: Changing your Gearbox oil.

Post by docjonty »

I did this today.
At yesterdays track day I couldnt believe the heat coming off the gearbox.
It was a bit of a pita , even though I have a little hand pump gear box oil filler .

Put in fully synth 75/90 and as stated, yes, changes feel much much better.
Diff next
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Re: Changing your Gearbox oil.

Post by warpc0il »

By "fully synth 75/90" I hope you mean a GL-4 grade oil, not a GL-5 or GL-4/5.

Some oils exceed the lubrication requirements of the 'box and, while you'd think this was a good thing, it turns out not to be.

The synchromesh relies on a known level of friction and "too slippery" oil prevents this from working.

The immediate result can be baulking of fast gear changes, while the long-term result is permanent damage.

This was confirmed by detailed strip-down analysis after gearbox failures following changes to Fuchs 75/90 gearbox oil.
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Re: Changing your Gearbox oil.

Post by stephorx »

What Pump is everyone using :?:
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Re: Changing your Gearbox oil.

Post by casey »

warpc0il wrote:By "fully synth 75/90" I hope you mean a GL-4 grade oil, not a GL-5 or GL-4/5.

Some oils exceed the lubrication requirements of the 'box and, while you'd think this was a good thing, it turns out not to be.

The synchromesh relies on a known level of friction and "too slippery" oil prevents this from working.

The immediate result can be baulking of fast gear changes, while the long-term result is permanent damage.

This was confirmed by detailed strip-down analysis after gearbox failures following changes to Fuchs 75/90 gearbox oil.
A timely reminder Dave, prompting memories of our trip up to Fuchs to see my poor gearbox in a million pieces :( - History now, lesson well learned and we don't want anyone to suffer the same issue as I did with my gearbox :thumleft:

For anyone not aware, don't use the wrong oil in your gearbox or you could destroy your synchros!

Don't look here if you are of a nervous disposition: http://www.rx8ownersclub.co.uk/forum/vi ... 29&t=46270
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Re: Changing your Gearbox oil.

Post by docjonty »

https://www.smithandallan.com/products/ ... -api-gl45/

This is what I put in the box.
Feels fine (much better) on the road.
I always had grunching going into first or second, that has gone.

What oil to people suggest?
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Re: Changing your Gearbox oil.

Post by casey »

Redline MT-90 (GL-4) is a tried and tested oil and popular with many people (I have used it for many trackdays without any issues).

The oil you have used is a GL-4/5 spec. Personally, I've NEVER risk using anything other than a straight GL-4 spec oil. The problems I had with my original box stemmed from using a GL-4/5 spec oil. The theory is that the extra additives in a GL-4/5 oil can make the oil too "slippery" for the RX-8 gearbox synchros to "grab" and do their job. Once that process starts it doesn't take long for the damage to be irreversible. Mainly affects up-changes 3rd-4th at high revs. Very noticeable on track, where it was impossible to engage 4th gear without letting the revs drop to around 4,000rpm, rather negating the track experience.

This is a good ring, see the sharp points:
DSC_0068.JPG
Part from my 'box showing damage to engagement ring teeth:
DSC_0039.JPG
This level of damage appears to have occurred on single session on track, before I realised what was happening and let the revs drop.

Result, replacement gearbox... :oops:
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Re: Changing your Gearbox oil.

Post by docjonty »

Thats just stupid prices.
I have seen this American snake oil mentioned on other sites from over the pond.

I`ll stick with mineral GL4 spec oil and change it after every track day.
As to the GL5 argument, I had a response re the effect on copper in syncro`s from the above oil supplier

"Hello,

I have passed this on to our technical department and their response is;

Our fully synthetic is formulated using an inactive sulphur, extreme pressure additive and has been for some time, this has an excellent result in the copper strip corrosion test, so no worries with this one.

So hopefully this answers your question"


Its not hard to change, so I`ll plumb for frequent changes after hard use, rather than belief in American oil fairies.
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Re: Changing your Gearbox oil.

Post by warpc0il »

The RX8 synchro issue has nothing to do with copper corrosion, that's all about the surface of brass cones being eaten away by the EP additives in some oils.

What we're talking about is the friction being too low for the synchro cones to work as designed.

I happen to choose Redline MT90, as I know that is doesn't have this issue.
There are plenty of other GL4 (mineral & synthetic) oils that also shouldn't have a problem.
From the specification given by Smith and Allan, their GL4/5 product is guaranteed to have this issue, unless they're lying.
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Re: Changing your Gearbox oil.

Post by docjonty »

Well, changed the GL4/5 stuff to castrol systrans GL4



The initial changed singificantly improved the shift

The castrol has made it even better
butter smooth gear changes

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Re: Changing your Gearbox oil.

Post by Dazza44 »

Umm that's intreasting I used the castrol then took it back out after about 1k as personally didn't find gear change very smooth at all I then put motul in, and noticed a considerable improvement

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Re: Changing your Gearbox oil.

Post by warpc0il »

@Dazza do you know what was used before the Castrol?

An oil change in the engine only replaces about 60% of the capacity, which is why we recommend a double-change, especially if the previous fill was suspect or overdue.

However, the gearbox oil change replaces about 85% of the capacity, the remainder being left tucked in corners and clinging to all the surfaces.

If the previous gearbox fill had been with an inappropriate oil, or with some sort of snake-oil additive, or was just worn out, then the benefit you found from the Motul after 1k miles might not be down to it being better than the Castrol but that the Castrol fill was having to cope with remains of the old fill and the double change fixed this.

I have recommended a double-change, with at least 100 miles in between, as a relatively cheap cure for gearbox ills, so far with a better than 50% success rate for really bad 'boxes and an almost 100% success for just notchy or noisy 'boxes.

When the prolapsed disc in my neck gets sorted then a double change with MT90 will be my first stop in trying to fix the 4th gear synchro that become a problem at Kirkistown Circuit back in July. [fingerscrossed]
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Re: Changing your Gearbox oil.

Post by Dazza44 »

Hi dave, I have no idea what oil was in car b4 I put the castrol in, saying that I got the car around 58k with not much record of anything the airfilter certainly hadn't been changed for some time (was filthy ) so I'd assume the gear oil hadn't been changed to I did seem to suffer crunching going into 2nd gear though now that is extremely rare but as you said the double change has probably helped

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Re: Changing your Gearbox oil.

Post by RenesisRaceBuggy »

It can take quite a while for a new gearbox oil to remove the film left by a previous one, especially if one with the incorrect EP additives has been used, as they literally bond into the surface of the synchro's
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Re: Changing your Gearbox oil.

Post by RobinPZ72 »

Has anyone used Shell Spirax S6 amxe 75w90 in there gearbox and transmission?

Just read the GL-5 of 4/5 bit, which has changed my mind a touch!

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Re: Changing your Gearbox oil.

Post by RobinPZ72 »

Right after much pain and suffering with gearbox oil I've finally settled on Shell Spirax S4 G 75w90! After a long head numbingly search it was staring right at me.
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Re: Changing your Gearbox oil.

Post by xamtex »

after having trouble with syncho crunch changing down to 2nd on the last 2 track days i changed the oil to redline today,no dramas...24mm to drop it and refilled through the gear lever hole.
needs some hard work now to see if its helped the issue.
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Re: Changing your Gearbox oil.

Post by V8 Power »

You may find your box is notchy when cold using Redline. Once warm/hot it will be like a very silky thing providing you have no synchro damage.
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Re: Changing your Gearbox oil.

Post by xamtex »

keeping fingers crossed on that.
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Re: Changing your Gearbox oil.

Post by GRIFF91 »

Hi All,

In regards to the 5-speed box. Do you have to fill from both the front and rear level holes?

Or is it one or the other?

It doesn't seem like the manuals on here provide any idea either as they're for the 6-speed.

I have previously changed my gearbox oil (it's been a few years, so i can't remember exactly) but i'm almost certain I only filled through the rear level...

Any clarity would be appreciated!