Hi Andy

The metal particles are most likely from the damper pads these are sacrificial
and the MGA ones fit from Leacy(?) MG, may be worth buying a couple as you have the with out oil at present.
A lot of racks were charged with grease as a lot of previous owners saw a nipple or two and filled them with grease, this may account for the thicker oil and the metallic particles. Oil is better, normally, than grease in steering racks and boxes, but a lot of people read the instructions only as a last resort.
Kind regards
Trevor

Thanks for that Trevor,

It was just that the oil which drained out of the rack was so much thicker than the modern 80-90 that have by me that I was unsure whether to use it.

I have now examined the oil under the microscope and it is heavily laden with metal particles - it looks like metallic paint! The steering feels very positive with no detectable slop, and the inner track rod ends although quite free have no looseness about them. The damper pads have not worn through to the springs as they had on my previous ZB! so I think I will try to flush out as much of the old oil with the new as possible without dismantling the rack any further.

Incidentally Opie Oils (www.opieoils.co.uk/) have Castrol EP90 at a reasonable price - £8.99/litre - but £3.50 P&P!

Hello Andy

The latest gear oils are fine for the steering rack, EP just means extreme pressure and the 80 - 90 is the viscosity within a temperature range, on the steering rack the pressure are fairly low, in comparison to say a rear axle.
The other thing is modern oils even Tesco's finest is better than what was available in the 1950s. So go with the modern oil whether multigrade 80-90 or straight straight 90 , Millers do a straight oil s do Castrol but at an inflated price.
Kind regards
Trevor

Replacing a split steering rack gaiter and have run out of my ancient stock of Castrol EP90 gear oil. The only stuff I have readily to hand is Castrol EPX 80W-90 but this looks quite a bit thinner than the old EP90. Is there still a source for straight 90W gear oil or am I worrying needlessly?