Almost universally no but . . .

I have found the occasional few that benefit from it - easily discovered whilst priming, if there's release agent on the item, paint just slides off, leaving unsightly pools of bare metal. Very much an oil and water thing. If that happens I just give them a quick rinse. I've experienced this with both GW (plastic and metal) and Essex. Never had a problem with PD or any others that I can recall.

It occurs that this happens with acrylics - I haven't used enamels since I counted my years in single digits but it occurs that the oil and water thing may be the other way round with enamels, making it more common. It was certainly one of those things oft advised in the 60s and 70s, along with baking and banana oil. Then again I daresay not only metals have changed dramatically but so have release agents and other contaminants.

I've also found that some metals benefit from a scrub before supergluing - Otherworld are a case in point, my Loctite won't bond them unless I wash the metal first. Just Otherworld, no-one else.

I have washed the ones I have painted up untill now, will try the none wash method for the next ups, PD Sudan forces, hopefully starting next week. They have been hibernating for some years now, as has the rest of the lead pile.