B6 Quattro rear differential oil

[allardj412]

Morning guys,

Bought my 2004 A4 B6 avant Quattro (1.8t 190hp manual) at the weekend. I'm absolutely over the moon with it.

I bought it knowing the rear diff seals were weeping and want to get this sorted ASAP. I have ordered the seals but my question to you guys is, what oil goes in the differential? I've read on quite a few forums that the grade is 75w90 fully synthetic. Would this be correct? If so what oil would be recommended?

[calum]

Morning guys,

Bought my 2004 A4 B6 avant Quattro (1.8t 190hp manual) at the weekend. I'm absolutely over the moon with it.

I bought it knowing the rear diff seals were weeping and want to get this sorted ASAP. I have ordered the seals but my question to you guys is, what oil goes in the differential? I've read on quite a few forums that the grade is 75w90 fully synthetic. Would this be correct? If so what oil would be recommended?

Recommended to change to 75w80 in the interest of cold gear changes. I'll be changing the gearbox and rear diff oil soon, I've bought this which will be enough to do both

Millers Oil TRX 75w80 Fully Synthetic Manual Gearbox Oil 5ltr | eBay

See this post Manual Gearbox oil query? | Audi-Sport.net

[Gazwould]

Recommended to change to 75w80 in the interest of cold gear changes. I'll be changing the gearbox and rear diff oil soon, I've bought this which will be enough to do both

Millers Oil TRX 75w80 Fully Synthetic Manual Gearbox Oil 5ltr | eBay

See this post Manual Gearbox oil query? | Audi-Sport.net

Wakey , Wakey Calum the man is after rear diff oil .

[Mario]

Recommended to change to 75w80 in the interest of cold gear changes. I'll be changing the gearbox and rear diff oil soon, I've bought this which will be enough to do both

Millers Oil TRX 75w80 Fully Synthetic Manual Gearbox Oil 5ltr | eBay

See this post Manual Gearbox oil query? | Audi-Sport.net

75w80 will be no different when cold than 75w90....the 75w indicates the viscosity when cold and the 90 indicates the viscosity when hot. So changing to 75w80 will only make the oil thinner when hot and have no effect what so ever when cold.

[Gazwould]

Very true of engine oil however completely incorrect for gearbox and diff oils , there is a big difference when cold in viscosity between a 75W80 and a 75W90 .

I suggest you look at some product data sheets or pick out two products and I'll show you the difference .

[Mario]

Very true of engine oil however completely incorrect for gearbox and diff oils , there is a big difference when cold in viscosity between a 75W80 and a 75W90 .

I suggest you look at some product data sheets or pick out two products and I'll show you the difference .

Have a read of the PDF from Opie Oils below. Page 4 specifically talks about gear oil and says....

AUTOMOTIVE GEAR LUBRICANT CLASSIFICATIONS

SAE J306 (Gear Oils)

Again, the classification is based on the lubricant viscosity measured at low and/or high temperatures. The high temperatures values are determined according to method ASTM D445. The low temperature values are determined according to method ASTM D2983 ‘Method of Test for Apparent Viscosity at Low Temperature using the Brookfield Viscometer’ and are measured in mPa.s (c.P).
Multi-grade oil satisfies the viscosity requirements of one of the W grades at low temperatures and one of the non-W grades at high temperature.
It should be noticed that there is no relationship between the SAE engine oil and gear oil classifications. A gear lubricant and an engine oil having the same viscosity will have widely different SAE grade designation as defined in the two classifications.

According to that the 75W determines viscosity at cold temps and the 90 is when hot.

Link below....

http://www.opieoils.co.uk/pdfs/viscosities.pdf

[Gazwould]

Ok here's the reality two G 052 911 , one 75W90 the other 75W80 .

Castrol Syntrans Transaxle 75W90 is 78 centistokes at 40°C some 75W90 often used in VAG like Redline MT90 is 90 centistokes hence my poor jap coupe cold shifts .

Fuchs Titan Sintofluid sae 75W80 is 49.8 centistokes at 40°C .

The 80 is thinner at the colder end , it's universal and I could give more examples between more different makes of transmission oil .

[rowdy-999]

Rear diffs are not that fussy. Just use a fully syn that's within spec.

[Mario]

Ok here's the reality two G 052 911 , one 75W90 the other 75W80 .

Castrol Syntrans Transaxle 75W90 is 78 centistokes at 40°C some 75W90 often used in VAG like Redline MT90 is 90 centistokes hence my poor jap coupe cold shifts .

Fuchs Titan Sintofluid sae 75W80 is 49.8 centistokes at 40°C .

The 80 is thinner at the colder end , it's universal and I could give more examples between more different makes of transmission oil .

40*c? I'd like to see how they compare nearer 5*c as they would be at 7am on the way to work....40*c is not exactly cold. That is still 15-20*c above our ambient summer temps in the U.K.

[Gazwould]

That's the only lower temp viscosity temperature data available , data sheets show 40 and 100°C .

The viscosity gap narrows higher up so one could assume it widens further below 40 .

Put into practice and feedback the 75W80 is the better cold shift quality because of lower viscosity at colder temperatures .