Originally Posted by X5only

Get this stuff - temporary assembly lubricant Seal O-Ring Rubber etc. This is a must have for any DIY mechanic. It critically eases the installation of components with seals etc and thereby preventing them being crashed/cut during application of force while installing the component. It's also used to install bushings with ease. It works miracles. You can use it to install even stuff without rubber and it just makes things significantly easy - they just slide through. I use it all the time and saves me time, effort and tears (literally). You just apply it sparingly and that single tube will last over many, many applications.

P-80 Emulsion Temporary Assembly Lubricant Seal O-Ring Rubber Assembly Aid | eBay

P-80® Emulsion Temporary Assembly Lubricant is a biodegradable assembly aide that eases installation of tight-fitting rubber and plastic parts by reducing the force needed for insertion. Once assembly is complete, the lubricant dries and the part returns to its original condition. P-80 Temporary Assembly Lubricants can be applied manually or automatically, by dip, brush, or spray techniques.
P-80 Emulsion Temporary Assembly Lubricant is used to install hoses, o-rings, seals, bushings, gaskets, grommets, grips, and many other rubber and plastic parts. Use P-80 Emulsion when a thin film of lubricant is desired.