David brown 995 1976

[DeanB]

Any one know what power steering fluid I should top up the reservoir with as I'm not sure what's already in there and the book states hyspin aws 32 or tellus 27 which I'm struggling to match with modern fluids or do I need to bleed the system and top up with new.

 

[Far Gloss]

I put ATF (automatic transmission fluid) in my DB 995

 

[agrimax]

The closest equivalent to Tellus 27 is just a standard ISO 32 hydraulic oil. Personally, I'd be using a 10w30 universal oil or the same as the engine. If the pump seal fails, at least this way you're not contaminating the engine with HYD oil.....

 

[Boohoo]

If you've no idea what is in the system I'd drain, flush and replace as some oils don't mix too well.
Our 996 has ATF in it, it was what was in it when we bought it. A lot of people recommend hydraulic 32, apparently it's recommended for later models, it's cheaper than ATF and it's what I would use if I was filling an empty system.
Engine oil does eliminate the possibility of contamination if the seal fails but it makes the steering heavier so I wouldn't use it.

Edit, just had a look at my operators manual and the general recommendation is for a hydraulic mineral oil of SAE 10W viscosity, which is hydraulic 32.