915 Gearbox oil change "How to"

[Uncle]

This is a dead easy job to do at home if you have some basic skills and tools. I am not going to start with jack up the car yadda yadda I'll just assume you know how to do this and if you don't you prolly should not be doing this job.

3 tips on this though.

Take the car for a quick drive to get the oil warm not hot just warm it will help drain it out.

Once you get the car off the ground and on 4 Jack stand. Get the front of the car just a little higher than the back this will help the oil drain out of the box a little. The other is take the rear wheels off or at least the left rear as it will make it easier to get under the car and you can also pop them  under the car. I do this as a "just in case" measure should the worst happen and the car somehow came off the stand.

 

Ok to the job at hand. Things you need.

OIl,drain pan minimum of 3ltrs,small oil pump,degreaser,rags,19mm socket,lead light/torch and a cardboard box. Optional Torque wrench and thread sealer and small funnel.

Tip. Line the drain pan with a clean dry cloth rag. White is best. This will catch and stray bits of metal or the like and give you a good idea of the health of your gearbox once you drain off the oil.

 

 

The most important part. Check if you can undo the filler plug before doing anything else. You don't want to be that person asking on a forum how to undo a stripped filler plug after you have already drained the gearbox now do you? Nope didn't think so.

 

So the filler its located on the left hand side of the gearbox and like the drain plug is a 19mm.

As seen here.. * It should be noted 915's are also fitted with a 17mm internal socket head filler plugs. Check yours before starting the job so you have the right tools before the get go,*

 

Take it out and give it a quick clean then place it in a clean location. I like to place them on my well worn socket set lid. Looks dirty but it is clean. Drain plug on the left and the fill plug on the right.

 

Next is the drain plug. Again 19mm and located at the bottom of the box.

 

Once you crack the nut place the drain plan under the nut and get ready for oil to come out of the box. This is the time the cardboard box and rags come in handy. Place them under the pan just in case. Because you have already removed the fill plug and the oil is warm will flow out quite quickly.

You don't need a photo of this its oil coming out of a gearbox. Expect 3ltrs of oil to come out.

 

Now the drain plug is magnetic have a look and see whats stuck to it. You are always going to have some metal shavings on the plug but hopefully no chunks of gear teeth!.

 

Filling the box. 

First off put the drain plug back in. Its going to be very messy if you keep pouring oil in with no plug in the bath...

I like to use the tread sealer here as an extra measure but I'll leave it up to you. Here you torque the nut up to 15 NM according to my service manual but really just nip them both up tight, Not as tight as you can get them with a 15 foot extention bar just tight.

 

 

Again because I like to keep my workshop clean here is where the little funnel come in handy. Most of them allow you to clip them onto the bottle. Well you get the idea from the photo..

 

 

Use the hand pump to put the oil in one litre at a time. You will need 3ltrs in the box. I just keep going until you get a little weep out of the fill point. Because of the location of the filler you can just pour the oil in like doing an oil change on a motor.

Nip the nut up and clean up any mess because a jobs not done until you have cleaned up. 

Simple as that.

[SteveF]

Uncle, you are a machine. Very interesting. Thanks for posting.

[Harvs11]

Excellent post, Uncle. Thanks for posting.

There's some good tips for those who have never done this seemingly simple job. It's the easy jobs that can catch you off guard.

[withers]

Awesome work Uncle..

"because a jobs not done until you have cleaned up." - love that!

[sydr]

Thank you for taking the time and trouble to share that.  I've been working on my cars all my life but still learn something all the time.  Good one.

[Red3.2]

Like it Uncle, Im sure most would like to see more of what you do along these lines

without putting you to any trouble.

Cheers

Steve.

[tk111]

Thanks for write up uncle.

I was going to do my gearbox oil in the next couple of weeks as I sometimes have issues with second gear.

I have been reading the Swepco vs Kendal threads elsewhere and was leaning towards Kendal.

Can you give us your opinion of the Nulon fluid in comparison?

[JustJames]

Nice one!

 

Wish I'd known about those clip-on funnels earlier.  The economy of the middle east might have worked out very differently.

[maxy]

Did the Nulon smooth shift oil make any noticeable difference to your gear changes?

[Uncle]

HAHA yeah James its the small things that make the job easier! TK, will do. Seeing as oil should be changed often I wanted to run somthing I can walk in to any shop and pick up off the shelf. 915 boxes are not somthing made of magic Porsche dust that somehow work in another way to any other gearbox and I don't buy into alot I read on P.P 'mericans are 10 to 15 years behind us on EFI use so I am not sure I trust them with oil yet!

[Uncle]

 

Did the Nulon smooth shift oil make any noticeable difference to your gear changes?

 

Can't tell you yet Maxy as I've still got some other jobs I want to so the car is still in the air.

[T-Man]

Good stuff Uncle.

 

Mods/Admin, how about a DIY section.

[Uncle]

Did the Nulon smooth shift oil make any noticeable difference to your gear changes?

 

Well today I found the time to go for a test drive and can report back. Yes it feels better to shift. My car shifts quite well but it did feel to me like it was better than before and seemed to select 1st a little easier. 

 

It should also be noted the plugs on Steamwolfs 915 are 17mm internal hex heads. Unlike my 19mm style. So it would pay to check your box before going to do the job.

[tk111]

Hi Folks, I was going to try this today but when I went to remove the drain plug I found this. Note the cracks and the rounding of the hex socket. Any suggestions?

[SteamWolf]

17mm inhex socket from gasweld. They are $13. If you are lucky it will undo ok. Order a new one before you remove it lol

[OZ930]

Just a silly question for the 915 gearbox users......is the internal plug and the external hex plug interchangable, that is same thead, different head.

 

If it can, I would change over.

 

Thought it may help

 

Cheers

[wasserkuhl]

Just a silly question for the 915 gearbox users......is the internal plug and the external hex plug interchangable, that is same thead, different head.

 

If it can, I would change over.

 

Thought it may help

 

Cheers

 

Not that I have tried, but I believe they are of a different size 17mm vs 19mm soI'd have to guess they aren't.

 

GREAT POST UNCLE ME LIKEY

[Glenn]

My 915 box has internal hex heads.  I changed the gearbox oil at home 6 months ago with no problem other than the fill plug had apparently been done up very tight and took a lot of effort to break out.  Recommend using factory torque settings only when replacing.

[IrisBlau]

Mine were also internal hex heads. Both same size, as far as I can see they are interchangeable. In fact I probably mixed them up at some stage.

 

Just to re-itterate Uncles excellent write up.

 

1) Remove fill plug before drain ( I had to use a breaker bar)

2) That tom thumb filler thing is essential. Cheap from SCA.

 

You can get swepco here, there are links in the forum. Good thing about swepco is that its blue and i noticed my cooler pipe was leaking. PITA.

Thanks

Ed

[clutch-monkey]

i have to do this on a G50 C4 car.. shouldn't be hard but double the plugs haha

[Cal]

915 boxes are not somthing made of magic Porsche dust that somehow work in another way to any other gearbox and I don't buy into alot I read on P.P 'mericans are 10 to 15 years behind us on EFI use so I am not sure I trust them with oil yet!

 

Now don't I feel like a twat for spending $114 on a bottle of Swepco! Mine is pretty bad though, so I'm hoping it does indeed have some magic Porsche flavoured unicorn jizz in it that does in fact coat my gear set!

 

Attacking this job on Saturday, albeit on a 901 box. Hoping I don't find one of those hex plugs under there.

 

Thanks for the write up mate.  

[wasserkuhl]

Swepco is now $85 for a gallon.

 

Changing my 915 today, the swepco agent is even delivering me the oil free of charge this morning!

[Caledonian]

Where do you buy it if you don't mind me asking, and does it really make a difference? 

[wasserkuhl]

There are local suppliers in every state.

 

Check this post out, I have gotten it from John Mallia prior to them setting up agents locally. Give him a call and they will provide you with the QLD agents near you.

 

 

Does it make a difference? YES.

 

It won't repair a worn gearbox, but it will slow the wear down. I just did mine, drained out the Valvoline 80/90 and put in the Swepco 201 80/90. The gearshifts are slicker and smoother. From cold It shifted without the need to double the clutch either(I do this to prevent wear on cold synchros and fluid).

 

Its not snake oil, its just good old texas tea developed for extreme heavy duty undustrial use, it just happens work very well with the 915's Baulk ring synchro design.

 

I have it in my 912's 5 Speed 901(dog leg) box as well and it made a significant improvement to that as well.

 

Ensure that your shifter and coupler are adjusted as well , the coupler has a bush in it that wears and the coupler develops play, which then materialises as a vague or sloppy feeling gearshift. A Re-bushed coupler that is properly adjusted will transform the car's feeling.

 

Swepco just gives you piece of mind that your synchro's and gears have the best protection you can put in a 915.

[Caledonian]

Thank you wasserkuhl, and if its good enough for someone who it OCD about oil its good enough for me:)

 

Agree with you completely regarding the coupler bushes, I changed all the the bushes on mine when i first got her as gear changes were like stirring porridge. It transformed the shifting experience! however six months later the shifting is getting a bit baulky? and while there was no evidence of slop in the gear lever i thought Id just check/adjust the coupler, and was surprised  to find the bushes starting to elongate already. I changed them (today actually ) with a set I'd gotten from the "Coupler Whisperer" and the shifting is fine again, amazing how 2mm of play in the bushes can make such a difference.

 

I let you know of the Swepco improves things for me.

 

Cheers