Ball Joint Lubrication on 560Sl, Advice?

[Alkraut]

I was looking at the upper and lower ball joints and the rubber seals on my 560SL. The seals look intact without tears or apparent seapage. There are no grease fittings, so I think they are "permanently lubricated". Can the ball joints be lubricated? Do I use a special needle tip? Technique? Or should I assume they are really permanently lubricated? The car has 80K miles. Thanks for any advice.

[nobby]

If the boots are in good condition and you see no evidence of leakage / seepage then why do you think you need to add grease?
I have in the past, with other vehicles, cleaned the boot really well, pierced it with a grease gun needle fitting and then sealed the hole with black sealant.