Diff Oil?

[Emackulation]

Ni hao.

Question: When changing the oil in my diff, what type do I replace it with and how much do I put in??? Just incase this makes a difference its a HSV LSD IRS 3.27 diff.

Thanks.

[Morton]

Personally, I'd be using a good oil, like Penrite Heavy Duty Limslip90 80w90. That's what I use in mine anyway. Perfect for LSDs. I tend to think Penrite do a slightly higher quality oil... and it's not ridiculously expensive.

[dufus]

According to my workshop manual they have a capacity of 1.7 litres.

[Emackulation]

Personally, I'd be using a good oil, like Penrite Heavy Duty Limslip90 80w90. That's what I use in mine anyway. Perfect for LSDs. I tend to think Penrite do a slightly higher quality oil... and it's not ridiculously expensive.

Thanks Morton, I sure do want a good quality oil. How many litres are in a bottle?

According to my workshop manual they have a capacity of 1.7 litres.

1.7L ey, what else does your manual say?

[dufus]

1.7L ey, what else does your manual say?

Not a lot LOL. The recommended oil is a SAE 90 Limited Slip Formula Gear Oil. If you want me to I can scan the procedure on how to change the diff oil for you.

[Emackulation]

Not a lot LOL. The recommended oil is a SAE 90 Limited Slip Formula Gear Oil. If you want me to I can scan the procedure on how to change the diff oil for you.

Yeah if you could that would be great, plus it would help other people if they are looking to do the same thing.

[dufus]

Yeah if you could that would be great, plus it would help other people if they are looking to do the same thing.

Ill scan it for you now

[dufus]

Here you go Mack and anyone else who is interested:



Taken from Haynes Repair Manual

[Emackulation]

Sweet, thanks mate. Seems like an easy process, with old cars it always makes me wonder how long ago it was changed...

[immortality]

80w90 is the standard diff oil really, if oyu want something a little heaver duty go to a 80w140 but what ever you use make sure it's rated for LSD use. if cost is no objective then i'd use Redline oil

[Emackulation]

80w90 is the standard diff oil really, if oyu want something a little heaver duty go to a 80w140 but what ever you use make sure it's rated for LSD use. if cost is no objective then i'd use Redline oil

And what would be the benefit of using this 80w140 over the stock?

[immortality]

i can see me getting flamed here but from what i understand the 80w140 will handle more pressure, basically it will handlemore loading between the gear working surfaces before you get oil film breakdown.

not that i'm an expert on the subject but it's what the diff guy put in my diff although he recommended i use redline oil

[GOTMYN]

i can see me getting flamed here but from what i understand the 80w140 will handle more pressure, basically it will handlemore loading between the gear working surfaces before you get oil film breakdown.

not that i'm an expert on the subject but it's what the diff guy put in my diff although he recommended i use redline oil

FLAME FLAME FLAME.........

Nah Only kidding, sounds right to me!!

[bradcad]

You are kinda right

it is easier to create higher shear resistance in a heavier gear oil, than a lighter gear oil. Is it worthwhile?

Some gear oils have developed many, many times the load carrying ability, or shear resistance of standard oils. Redline is designed for so many times the load carrying ability of standard oil. Other brands have similar abilities, some exceeding 3200 pounds, whereas standard is around- 80? 90 pounds. So using these oils means using a thicker oil is somewhat obselete.

So to answer the question- if you buy a decent oil, no you dont need to go for a heavier oil.

And as an interesting side fact, 80w90 gear flows similar to (about- cant remember cts for each) 10w40 engine oil- or thereabouts. Different final uses of oil means different grading is used.

Also, the faster the gears, the lighter weight oil is required. The slower the gear, the heavier oil is required.

[beardy91]

I recommend that you use Redline Light Weight Diff Oil or Redline Heavy Weight Diff Oil if you do a few skids or drive a bit harder than the average Joe. If you want something cheaper, try Castrol LSX90 as this works a treat too.

[Emackulation]

Thanks for all the good info!!!

[immortality]

I recommend that you use Redline Light Weight Diff Oil or Redline Heavy Weight Diff Oil if you do a few skids or drive a bit harder than the average Joe. If you want something cheaper, try Castrol LSX90 as this works a treat too.

i used castrol diff oil in the missus VS and it's now got noisy pinion bearings, i used it cause someone gave it to me (freebie) instead of the penzoil 80w90 i normally use in standard diffs. i'll never use the stuff again as it's now going to cost me more $$$ to replace bearings then to use decent oil.

[V85000i]

Mack, don't remove the rear housing because that is what holds the rear end up. all you have to do is remove the bottom bolt from the rear housing and let all the oil drain, then put it back and fill it up through the side where the big bung thing is, once oil leaks out the hole it is full (make sure it's on level ground)

also you need to use the right type of oil because IRS diffs have rubber seals in them and if you use the wrong oil it can damage them and cause leaks.

[Reaper]

Just a note, the procedure in post #8 is for a live axle rear end. Mack's car is IRS which will be different.

Reaper

[Emackulation]

Just a note, the procedure in post #8 is for a live axle rear end. Mack's car is IRS which will be different.

Reaper

I noticed that also, cant be too different can it?

[dufus]

Just a note, the procedure in post #8 is for a live axle rear end. Mack's car is IRS which will be different.

Reaper

I didn't even think about that, im glad you pointed it out.

[Reaper]

I noticed that also, cant be too different can it?

It's not just a matter of taking the hat off the back of the housing. This is the best pic I can find right now: Shameless use of ebay add to illustrate what I want!
Check out the 3rd one. It looks like there is a drain plug at the bottom (unless it is upside down). Whack the car on axle stands and have a look under there - it should be pretty self explanatory. Check out a gregories manual or something for the capacity you need.

Also make sure you know where the re-fill bolt is before you drain it. I used to have a very long pvc tube and feed it into the refill holes of g/boxes etc from outside the car to make the job easier.

Reaper

[V85000i]

your just lucky i happen to still have pics of my diff on the computer, you can see the filler plug in the first pic. and the drain plug is the lowest one on the rear hat you can just see it in the second pic, so remove the drain bolt/plug let it all drain, then put it back and fill up the diff in the filler hole until it overflows, do it on level ground too

[bradcad]

Had a think about it over the weekend, and I thought i should qualify something

faster gears- lighter oil
slower gears- heavier oil
higher pressure- heavier oil
lower pressure- lighter oil
higher operating temperatures- heavier oil
lower temps- lighter oil

So its a mix of all of the above which specifies what oil to use. Keep in mind a better quality oil may allow you to use a lighter oil in the same unit. ie. the cheapest VS the best- cheapest will show far higher operating temperatures than the better one, therefore the oil will not thin out as much as the cheaper. It is a cyclic effect- the cheaper oil allows more friction to be created between moving parts. Friction = heat. Heat thins oil. Thinner oil = less ability to resist shear. less shear ability = more friction. friction = heat. Heat means oil also degrades quicker- wears out. Friction produces more contaminants. Degraded oil + contaminants = friction. friction = heat.

Increase pressure and you will need a heavier oil. The same diff behind a standard 6 driven by a granny will not have the same requirements as her grandson driving it up quarter miles constantly with a V8 stroker pushing it.

One final factor for choosing the correct diff oil- fluid friction. The heavier the weight of oil, the more fluid friction is pruduced, particularly if the unit is not reaching temperatures which the oil was designed for.

[Fu Manchu]

... and on a simpler note,
why does Diff oil have to stink so much