I probably go through this headscratching selection process every time I top up my power steering fluid: The Owner's Handbook recommends Shell Donax TA. https://www.mil-specproducts.com/documents/712_PDS-DONAX TA.pdf Not sure, but I may have read somewhere that it was Dexron II grade ("D2"). I Google Shell Donax TA and find it has been superseded by Shell Spirax S2 ATF AX. I Google Shell Spirax S2 ATF AX and it is not available in Australia (only the UK, South Africa and a few other countries remote from me). Here's the technical bulletin on Shell Spirax: https://www.zoko.co.il/sites/zoko/UserContent/files/213212.pdf I do a broader search for Shell Spirax and find it comes in dozens of different variations, so I need to do more Googling. Google produces this article: https://www.cartechbooks.com/techtips/autotransfluid It has the following text: I also have to worry about mixing mineral oil based products with fully or partially synthetic products. I believe Dexron II was mineral based. I think I have used Motul ATF VI (fully synthetic) in the past and it's readily available. Here's the technical data sheet: https://s3-eu-west-1.amazonaws.com/motul-production2/images/product_descriptions/technical_data_sheets/48940/ATF_VI_(GB).pdf?1511170487 It is a Dexron VI grade (or "D6") fluid, so I'm not sure if it is the right stuff (see above). It's recommended for Mercedes vehicles, so you would think it would be good enough for the F355, but Ferrari is not on the tech data sheet. So now we are back to square one. I realise that the power steering system is probably not subjected to the wear and tear of gearboxes, but I'd like to be sure I'm picking the right stuff. Any recommendations? Thanks!