What fluid for hydraulic jack? - martint123
Hi folks, I've got a scissor lifting workbench that I use to work on the motorbike (not sure what it was originally for, LINK by name.) I got it for virtually nothing last year. Leaking seals.

It has a horizontal jack with built-in pump and a two stage ram (two diameters, wide for the large initial load and narrow for the remainder). It had been out of service for some time and was leaking fluid from the ram. I took it apart and cleaned up the bores and pistons and took it to a friendly hyraulic engineering company who measured things up and got some new seals for me (and a quart plastic milk bottle of fluid).

The seals still weep a bit and at some time I'll try one of those honing tools seen in halfords and the auto tool catalogs to see if I can polish the bores a bit as I suspect there may be some rust pitting from its lack of use.

At last the question. What is jack oil???? Halfords sell it at quite a price for a smallish quantity. The local motor factors haven't a clue. The jack holds about a pint and a half.

Would powersteering fluid do?? - it seems roughly the same viscosity and a couple of drops mixed ok on the bench.

Any info welcome, regards
What fluid for hydraulic jack? - David Lacey
Only use proper jack oil - it's not worth the risk.

Any garage equipment specialist will stock it - Partco definately do.
What fluid for hydraulic jack? - Dynamic Dave
I agree with David Lacey. I recently bought some Jack Oil to top up my trolley jack from my local Motorists Centre, so it seems to be readily available. IIRC, around £4 for 500ml.
What fluid for hydraulic jack? - NormanB
Okay I will stick my neck out here!

What is special about the oil for a hydraulic jack?

Surely all that is needed is one that is free from particulate contamination and compatible with the material that creates the piston seal and the cylinder/ram seal.

Until you fix the leak I would use a clean straight mineral oil.

(leaving aside the corrossion issues you could use water in a hydraulic jack!)
What fluid for hydraulic jack? - Richard J
There is nothing special about jack oil. It's probably a straight hydraulic oil with a ISO viscosity of 32. This type of oil is very cheap if bought in bulk. However, for the amount in a jack, just pay Halfords price. Don't use transmission fluid (the red stuff), as this will probably ruin the seals. I agree with NormanB; a clean mineral oil will be OK, but why risk it to save a couple of quid ?
What fluid for hydraulic jack? - martint123
Thanks for the replies so far. Matybe forgot to mention in the first post.
(1) It takes about a litre of fluid (more than I thought). That I haven\'t been re-using when I strip it down.
(2) The workbench has a safety interlock ratchet that locks the mechanism in 1 inch increments on the way up - tested with three hefty blokes bouncing on the top.
(3) it doesn\'t weep much when supporting weight (with safety ratchet disabled, but does seem to lose fluid on the way up and down.

I\'ll pop down to some more motor factors to see if I can get a gallons worth.

Thanks again

What fluid for hydraulic jack? - Clanger
This goes agiainst the feeling in the thread, but, for what it's worth, I have used green LHM fluid in my trolley jack for nigh on 20 years with complete confidence. Worse yet, it's from the brake bleeding bottle so it's been round the houses once already.


What fluid for hydraulic jack? - jc
Look in your yellow pages for a local hydraulics supplier;they'll probably fill a container for you.


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