I used the new 'PC' Gunk some years ago - both in aerosol & liquid form; it was useless. Many years ago my (now late) parents came to stay, bringing with them a box of 'stuff' that I had left in a cupboard when I moved to Scotland in 1972 . . . There was a tin of 'original' gunk there. I still have it, it looks like liquid tar, smells like 'Gunk' and probably works. Its the way of the world with 'Health & Safety' deciding that the Plebs can't be trusted with stuff unless accompanied by a man in a high-viz jacket carrying a clipboard.
Try buying paint stripper that works . . That's gone the same way.
And oil-based exterior gloss paint that needs white spirit for washing the brushes.
For de-greasing engines, gearboxes, chassis and anything (apart from Aluminium) really I use 'Ubik 2000'. It will take the skin off your hands as its quite caustic but it works! A local Engineering Works was banned from using it by the Health & Safety Police - so it must be good
It will dissolve Alloy, so use it with care and wear gloves
My avatar shows the late Len Rich in 1970 with the bike I now have - a 1958 Ariel VH