Haha mine are 45 years old and still look fine.

If you want lurethane to last longer without crumbling, grease it, even if the package doesn't say so.

[edit] Polyurethane does not like being compressed hard like in a `live' rubber joint (eg Mk2 bottom arm rubbers). It will split and crumble. Most replacement poly bushes where used on modern cars are greased on assembly.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Modern rubbers can be amazing, even compared to just 20 years ago. They're more related to plastic engineering than oil and latex, but the materials are great...if you want to specify and pay for it as a middle man supplier...

Saying that, the Minispares rubbers I fitted 8 years ago are still going well, but I don't use the car as a daily driver either...

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Have a look at any modern two-piece engine steady rubbers after a year or three of fitment - absolute junk.
This is down to the CARBON and CLAY content added to rubber to lessen the material cost of "rubber".
And we pay for it by being shafted with inferior product.

It's not limited to rubber, either....