Grumpy, some of the vintage vehicle parts mobs seem to have one or two types of these small 'spring lid oilers', for specific vehicle applications [e.g. Model T Ford steering].

But this mob have quite a range; http://www.gitsmfg.com/catalog/oil-hole-covers/

Oz distributors; http://www.cebeco.com.au/products/tank-vents-and-fittings/small-tank-fittings

Blackwoods can usually get anything in the engineering sphere, but they surely know how to charge...

Cheers,
Gadge

"ODK Mods can explain it to you, but they can't understand it for you..."

"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."