Transmission Oil Alternatives

[Charlie san]

Hey guys,

I know there was a similar topic on this I while ago but I thought there could be more of you now who are taking care of your own car. As I've gathered my 2007 V8V needs 4 litres of Castrol BOT 270A, but this is impossible to get. Another option the Shell Transaxle, as stated is the Manual, just make sure it is not the Spirax, but Transaxle. To adding to the confusion, Shell now calls it Spirax and dropped the Transaxle range.

Would be nice to see what are the others use, am I safe to say all I need is a good 75W-90 viscosity oil that is GL4 or GL5?

Thanks for all your help guys!

Edited by Charlie san on Sunday 12th March 19:07

[V12JDC]

As you have a mechanical LSD then yes a good 75w90 is fine, Castrol Syntrax longlife is good

[telum01]

I use Motul for everything in my car. They're a top-tier brand with top of the line products, and their Gear 300 75w90 gear oil works great.
Aston switched to the BOT270A to help alleviate the stiff-shifting issue when the gearbox is cold. The new oil is basically less viscous when cold, so it's a little easier to shift even if the gear oil hasn't warmed up yet. (The also altered a portion of the shifter to change the leverage point for shifting inputs.) Motul's Gear 300 is the least viscous 75w90 gear oil I've found at cold temps, so it's the most similar to BOT270A that I've found.
Gear oils that have LSD additives (limited slip differentials, not drugs) tend to be more viscous because of the additives. LSD additives are there to help protect the oil from the actions of the diff, but in turn make the oil more viscous, which makes it more difficult to shift when cold.
Also, GL-5 gear oils (those with LSD additives) can be corrosive to yellow metals, which are found in the synchros of the transmission. Some GL-5 gear oils are corrosive, some are not. GL-4 gear oils (those that do not have LSD additives) don't have that issue.
As for Castrol's product names... good luck keeping up with them. They keep rebranding things, plus they change them for various markets, so it's a huge pain to know for sure what exactly you're getting unless you have the bottle in front of you.

Edited by telum01 on Monday 13th March 13:34

[Charlie san]

Thanks guys for all your input!

I do find it odd -some insider might explain the reason behind it- that big brands as Shell, Castrol and Mobil are naming their products different way in different countries. Also, the available/ non-available in your country driving me crazy.

Had the same story with my Honda S2000 when it turned out the engine oil recommended is not available in Europe... But you can cope with that issue easier than finding the right oil for your Aston gearbox/differential.

I like the idea of the Motul option, will definitely have a look!

Thanks again chaps!