gearbox and diff oil

[Pirvu Eugen]

I have used Castrol 75w90 full synt for the gearbox and 75w140 for rear diff. o problems till now.

[vonbeck]

just looked on castrol web site, they dont list either the taf-x or the saf-xj does any body know where to purchase

[Tom_]

which oil for rear diff on 7a cq?I cant find any info in ETKa

[Dybro]

What I have found is that the G 052 911 A transmission fluid is 75W-90 GL4+ (01e boxes + others) and translates to the VW-TL 501.50 norm.
Castrol's taf-x 75W-90 is now called Syntrans Transaxle 75W-90. The castrol transmission fluid carries the vw-tl 501.50 approval. It wouldn't surprise me if Castrol actually developed this oil in collaboration with VW AUDI.

The motul gear 300 75w90 should be very good and properly better than the castrol. Anyone using it..?

The rear diff calls for G 052 145 A and is 75W-90 GL5 also, don't have any TL-norm though. Some Castrol Syntrax 75W-90 should be good enough I think.

I can see that some of you like to use 75W-140 in the rear diff. Any good reason for doing that.??!

[Tom_]

what about this Valvoline HP GL-5 80W-90 ? I have a good experience with a engine oil 10W60 VR1 racing so i guess,that this diff oil can should be good enough

[Dybro]

Well.. That valvoline 80w90 is a bit thicker than 75w90 until both oils hit 100 deg.C

75w90 is ~90 cSt@40 deg.C and ~14 cSt@100 deg.C
and
valvoline 80w90 hp is 135 cSt@40 deg.C and 14,5 cSt@100 deg.C
Its datasheet doesn't say anything about base oil quality so it might be regular semi-synth or dino. It carries MB, MAN, Scania and ZF approvals, and the datasheet says this oil is for eg. trucks and busses.
I don't think it is crap-oil but it should be possible to find something better and in the same price range too.

http://www.valvoline.nl/media/HP-Plus-Gear-Oil-GL-5-80W90.pdf

[Tom_]

OK so now i am choosing between :

Mobilube 1 SHC SAE 75W -90
Motul GEAR 300 75W-90
Liqui Moly (GL4+) SAE 75W-90

[Dybro]

If it was my choice, then it would be this:
1st Motul GEAR 300 75W-90
2nd Liqui Moly (GL4+) SAE 75W-90 this one carries vw-tl 501.50 approval(the right stuff for the tranny )
3rd Mobilube 1 SHC SAE 75W-90

1st and 2nd is a difficult decision but the motul seem to be quite popular among enthusiastic sport car drivers/racers. But again, the liqui moly got the vw-tl 501.50.
If the motul isn't much more expensive than the liqui moly, I would go for the motul.

[Tom_]

Dybro : ok, i choose between Liqui moly and Motul...if the moly have the right one specification

[Dybro]

#Tom

Just because the Motul don't carry the vw-tl spec it doesn't mean that the Liqui moly is the best oil. I only means that the Liqui moly has been tested and that the result was good.

I hope I didn't confuse you with the oil specs, trannies(transmission) and diffs(Rear differential), but I will try to make it clear anyway....

Some gear oils can have a single API-GL rating like GL-4 or GL-5

GL-4 oils is safe to use with "yellow metals" like our synchro rings in the transmission.

GL-5 isn't safe to use in transmissions that have brass or similar metals inside. The reason for this is the GL-5 additive package which can attack copper and copper-alloys.
Typically GL-5 oils are tougher than GL-4 when it comes to handling extreme loads and high temperatures.

But we also have oils that is API GL-4+ approved (aka GL-4/GL-5 or GL-4/5). This is an oil which is safe for "yellow metals" but it also meet the requirements for the GL-5 rating. This means it is suitable for transmissions and rear differentials

The Motul gear 300 and the Liqui moly you mentioned are both very good oils, and they are both suitable for transmissions and differentials. So just get which oil you like the most.

[Tom_]

Dybro : Thank you, now i have clear about it.

[Chris5044]

Thx for this link guys.. I've gone for some Motul for both g/box and Diff