Change spacing around binary operators

I'd like to change spacing around binary operators and this issue is discussed there:
How to change default for spacing around binary relations?

Is there way how to change spacing in math and displaymath separately?

\everydisplay can be used to make a different setting for displayed equations:

\documentclass{article}

\medmuskip=0mu %
\everydisplay{\medmuskip=10mu\relax}

\begin{document}
\centering
$a+b=c+d$
$a+b=c+d$
\end{document}


• Best solutions are the simple ones. Thanks a LOT. – Crowley Jul 10 '13 at 7:59