Diff whine and oil change interval

[rowan194]

I changed my diff oil today to see if it would get rid of the whine at about 80-90km/hr... it hasn't totally eliminated it, but the noise is softer now. Thought I would give it a try as it only cost me $25 for a couple of litres of oil, and I already had a hand pump.

Anyway, I got to wondering. How often should diff oil be replaced as part of routine maintenance? I'm assuming what I drained today is factory original, so it's done nearly 200,000km. It looked in pretty good nick, a bit darker than the new stuff, but no sludge or bits of metal coming out of the drain hole.

[Day-mow]

did it smell mega bad? promeams its fresh ish. mine was black and smet so bad!!!

[rowan194]

Nah, mine was a medium-dark brown, it did have a smell but it was just like used oil smell around a farm... nothing too horrible.

In contrast, the TQ95 transmission fluid I topped up with the other day smells like cat pee.

[rowan194]

Forgot that I took a pic. It was a little windy that day.

[Day-mow]

wow. thats healthy.mine was mega black. if you have your hand/service manual that comes with the car it should say how often to change the diff oil. also what do you do wit the car? do you drive it hard or tow lots? might be worth using something a bit more then average oil if you do.
also something to remember do you need to use an additive?

[rowan194]

Mine is just used for relatively sedate everyday driving, no tow bar.

I don't have a service manual, but my Gregory's manual just says to inspect for rear axle oil leaks... no clues on when it should actually be replaced.

The diff has been whining since I got the car 6 years ago @83,000km.

I used this... looked around the area for diff/manual trans additives but couldn't see anything.

http://www.nulon.com.au/products/Gea...ferential_Oil/

(I don't have LSD, but this can be used for conventional diffs too)

[Day-mow]

oh yeah looks the goods then!

how'd u fill it back up? beer bong it or?

[Mr Hardware]

rowan194, are you sure it's the diff? does the noise change whether it's power on or power off? does it change if the car is in neutral?

because i have a whine at 92-96kmh. i'm relatively certain it ain't the diff however, i think it's the planetary gears in the trans.

[rowan194]

Originally Posted by Mr Hardware

rowan194, are you sure it's the diff? does the noise change whether it's power on or power off? does it change if the car is in neutral?

because i have a whine at 92-96kmh. i'm relatively certain it ain't the diff however, i think it's the planetary gears in the trans.

I only hear the noise when accel is applied, even just really lightly. I can move it from 0% to 5% then back to 0% and hear it come and go. So you would think based on that behaviour it may be something to do with the trans, but the noise is definitely coming from the rear. It's a high pitched noise rather than the sort of whine/scream you hear the auto make when you take off in first.

It was diagnosed by one mechanic as the drive shaft, and that was replaced (probably with a used one) under the dealer's stat warranty, which improved but didn't obliterate the noise. Another mechanic diagnosed it as the diff and wanted me to spend several thousand dollars for a changeover unit... I politely declined.

One reason I changed the oil was that I thought at first glance the caked on crap you can see in the pic was leaking diff oil. I thought it was like grease rather than running oil which is why I thought it was leaking. Anyway, turns out it was just mud, and I now know that diff oil is a bit thinner than I thought

[rowan194]

Originally Posted by Day-mow

how'd u fill it back up? beer bong it or?

Hand pump.

http://www.supercheapauto.com.au/onl...spx?pid=284708

Gets a bit tedious after you've hand pumped in nearly 2 litres, but you don't have to do it very often...

I also used this to check my trans level.

[Day-mow]

i bet my diff is louder. hahaha. makes some horrid noise's.
i got quoted $1600 for a new diff. i think im gonna look around to make sure its the diff 1st.

[Mainlube]

Originally Posted by rowan194

I changed my diff oil today to see if it would get rid of the whine at about 80-90km/hr... it hasn't totally eliminated it, but the noise is softer now. Thought I would give it a try as it only cost me $25 for a couple of litres of oil, and I already had a hand pump.

Anyway, I got to wondering. How often should diff oil be replaced as part of routine maintenance? I'm assuming what I drained today is factory original, so it's done nearly 200,000km. It looked in pretty good nick, a bit darker than the new stuff, but no sludge or bits of metal coming out of the drain hole.

Diff oil change

60,000 klm for abit of track work
100,000 klm for normal

Hope you flushed

Cheers

Steve

[Mr Hardware]

Hope you flushed

you sound like my mum

[rowan194]

Originally Posted by Mainlube

Hope you flushed

Nah, straight replacement. I'd be more worried if it came out in globs. If 100,000km is the normal service interval then this is the first time (at 195,000km) it's been done.

[Mr Hardware]

Yeah my car displays the same behaviour, only a tiny bit of throttle is needed to invoke it, comes from the rear of the car. However i'd describe it as more or less the same as the trans whine through first. Which, if you listen, also sounds like its coming from the rear of the car.

[Day-mow]

did you use the addative?

[rowan194]

Originally Posted by Day-mow

did you use the addative?

No, couldn't find it at supercheap. It's simple and cheap enough to change that if I run into the additive in the future I'll just redo the oil.

[Mainlube]

Originally Posted by rowan194

Nah, straight replacement. I'd be more worried if it came out in globs. If 100,000km is the normal service interval then this is the first time (at 195,000km) it's been done.

With Mainlube not other oils, they can quote their own usage

cheers

Steve