Diff oil level

[guye]

Newbie question. I need to be sure the oil level in my diff is OK.

I know the diff oil is meant to be filled to the bottom of the fill plug (or max 6mm lower), however it is practically impossible to see in!

I've made a small dipping wire but I think it gets 'oiled' when I touch the entrance to the hole, so am not confident this is accurate.

Best effort was to shine a torch, and then spin the wheel so the gears upset the oil to create a ripple, but I'm still not confident.

I filled it from empty with 1.15 litres (1 litre oil and 0.15 LSD additive). Its a 3.45 LSD ZF diff.

I could buy another bottle, of oil and fill it till it drains, but that seems pretty primitive and wastefuly (doubt I'll use the rest of the bottle for years!).

So I used my Aldi special inspection camera and took a crappy picture while I was turing te gears again. Hopefully some of you will recognise the gear and the oil level and tell me it is full!

The arc at the bottom is the lip of the fill hole.

[Aussie Mike]

The normal procedure with most diffs is you keep filling till it starts to run out of the fill hole then screw the plug in and clean up the spilled oil.

cheers

[1795]

Ditto. I have also used the primitive stick your pinky finger in the hole and see if you touch any fluid with the bottom of your finger method.

[kevins2]

Take a twist tie and bend one end into a U shape. That will essentially act as a dip stick.

[dhs.buckley]

Same Aussie Mike, fill it till it comes out the plug and put the plug in straight away, same with the gearbox.

[stiffy]

Guye,


What Aussie said.

I have changed the diff oil in all my cars ( the hoist make it easy ) and use this

Method. I also wear a face mask as the smell of diff oil makes me puke....

Stiffy

[Towmaster]

The fluid is thrown around massively by the spinning gears anyway so it's not that critical. as long as it is close to the level of the hole then it should be fine. But as the others have said, yep, fill it till it starts to run out then put the plug in.

[guye]

Thanks guys. So seems the scientific method is most popular. "Stuff it in till it comes out the other side"

[Modena]

Ensure you are using the right oil bud

[patrickt]

Originally Posted by Modena

Ensure you are using the right oil bud

... and the right limited slip additive.

[David Hodgson]

Originally Posted by stiffy

I also wear a face mask as the smell of diff oil makes me puke.... Stiffy

I worked at the local govie bus workshops in the 80's and several brands of buses ran a Wilson semi auto box with a simple fluid flywheel coupling (like a torque converter). This oil didn't circulate with the g/box oil and you had to change it separately. The lube guys would never change this oil during a service, and when you drained it during a G/box change it was worse than a sewer or café grease trap. We would dry reaching 'till we could get rid of it. The stench hung around the w/shop for a couple of days.

[Jaydee]

If you wipe a little chalk on the dip stick first, it'll be easier to see the level.
I still remember servicing a volvo for it's first 1000 km service. We had to change all the oils. When I removed the sump plug for the diff, not one drop came out. It was never filled from the factory. It wasn't even noisy.
JD

[stephen low]

Just curious in terms of the comments above about using the right "Oil and "Limited slip additive".

For my 50+ year old Jaguar LSD, after I had it serviced as part of my rebuild, I was told to use a specific synthetic for the first 500kms and then to drain and fill with an AMS oil and only do changes thereafter every 10 years.

These comments came from the jaguar specialist that originally serviced the diff, so I am assuming the bloke knew his stuff in terms of the right oils and grades.

So the question I guess is more around the additives comment.

If the right oils had been specified why include an additive?

[Gav]

I thought the additive thing was a load of crap until I was trying to work out why my newly rebuilt LSD didn't feel right, it was kind of notchy when it was driven around at low speed, it was really noticeable when I was manoeuvring around in the pits at Winton one year.
Anyway I added a bottle of Penrite diff additive to the diff and it was immediately apparent that that was what the issue was.
Jag's may be different but a BorgWarner 75 LSD needs it.

[guye]

Yep. I triple checked the oil and additive. Hope it's right 'cause it's in now. And the drain plug is really difficult to get at!

[patrickt]

All limited slips require an additive. The outboard braked rear that I have in my car is based on the Salisbury Power-Lok and requires the Amalie LSD additive, which is hard to find, or the GM additive, which is easy to find. But you absolutely, positively have to have an additive in there or you get sticking, ratcheting, and other rear end misbehavior.

Here is an interesting link dealing with the Jag rear leather and rubber seals and their compatibility with synthetic gear oil (and synthetic LSD additives). As always, take with a grain of salt. XJ-S Final Drive

[patrickt]

It's easier to find hen's teeth than it is this stuff. I don't know why. Even the on line Amalie store doesn't carry it. Amalie Oil Co. - Limited Slip Axle Concentrate

[Modena]

I haven't purchased any so I am not sure (my diff was purchased brand new and was already filled), but I believe if you get the OE specified oil from Holden for your ZF diff it is all in one container (by the litre), I assume it would already have the additive in it, or was designed like that from the get-go. This is what I meant when I said the right oil. I think it's about $70 / litre.

[stephen low]

Interesting!

Was so long ago I've no idea what the Jag specialist recommended for the break-in oil for the first 500kms.

But the diff has been filled almost all this time through rebuild - well at least since March 2009 according to my spreadsheets.

But I held onto the empty oil container he gave me and which is an AMSOIL series 2000 product he suggested be used after diff break-in.

The specialist said to use this from 500km until the next diff oil change at 10,000km!

Its a 75W-40 synthetic but doesn't suggest it contains any additives and is recommended for GL-5 or MT-1 specified applications plus others.

Given the guy worked on Jags as his stock in trade I'll stick to the recommendation unless someone can demonstrate a compelling reason otherwise.

[patrickt]

Originally Posted by stephen low

Interesting!

... and for the other side of the coin, see: Dealing with your Jaguar Differential. A quote:

We also feel that the use of a synthetic gear lube, of the appropriate viscosity, will extend the life of these diff output or carrier bearings.