Join Date: Aug 2011
Location: Albuquerque, NM
Ferrari Life Posts: 11,881
Rik- In general on oils and hydraulic fluids, you want to stick with the same manufacturer/refiner when you add fluids. If you had synthetic oil by Quaker State (Q, maybe), you are actually better off adding a Quaker State non-synthetic to top off than you are using a synthetic by another manufacturer. This is because many oils meet the same standards, but use different additives to meet those standards. Different manufacturers' additives may not be compatible and can react together, degrading lubrication properties.
Same for the automatic transmission fluid used in power steering systems. The latest recommendation for power steering systems in Ferraris is Donax TX, which is a synthetic transmission fluid meeting GM's Dexron III standard, mentioned in your 456 OM as AGIP Dexron. If you use a different ATF, like Valvoline, it would be perfectly safe to mix their Dexron III ATF with their Dexron VI ATF if you could not find the Dexron VI to top off. In general on ATF, a manufacturer's later spec fluid is back compatible with its earlier spec fluids, but it is not compatible with another manufacturer's fluid. So for the Valvoline example, you could mix any of their fluids that meet Dexron III or higher standards. I actually run Valvoline Dexron VI in my power steering system.
Incidentally, for those of you with cars earlier than 1996, coincidentally when Shell became a primary sponsor for the F1 cars, here is the tech bulletin on the switch from AGIP to Shell products.
Present: 575M 135171
Past: Dino 246 GT 02984, 365 GTB/4 14009, 308 GTS 25125
Every day I look around, and if nobody is shooting at me, it is a pretty good day.