{"id":9,"date":"2026-09-15T09:00:00","date_gmt":"2026-09-15T09:00:00","guid":{"rendered":"https:\/\/llfgrease.com\/news\/mixing-greases-read-this-before-you-top-up\/"},"modified":"2026-09-15T09:00:00","modified_gmt":"2026-09-15T09:00:00","slug":"mixing-greases-read-this-before-you-top-up","status":"publish","type":"post","link":"https:\/\/llfgrease.com\/news\/mixing-greases-read-this-before-you-top-up\/","title":{"rendered":"Mixing Greases? Read This Before You Top Up"},"content":{"rendered":"<p>It happens on every maintenance floor: the specified grease is out of stock, a similar-looking pail is on the shelf, and the bearing gets topped up with whatever is available. Three weeks later the bearing runs hot, grease leaks past the seals, and nobody connects it to that one-time substitution.<\/p>\n<h2>What actually happens when greases mix<\/h2>\n<p>A grease is roughly 80% oil held in a thickener scaffold. Two greases mix badly in one of two ways:<\/p>\n<ul>\n<li><strong>Matrix collapse:<\/strong> The new grease&#8217;s thickener interacts with the old one&#8217;s, and the scaffold loses rigidity. The grease softens dramatically and flows out of the bearing &#8211; leaving it unlubricated. Lithium meeting polyurea is the classic case.<\/li>\n<li><strong>Matrix hardening:<\/strong> The opposite failure &#8211; the blend stiffens, the bearing starves, and churning heat builds up.<\/li>\n<\/ul>\n<p>Either way the failure is delayed and quiet, which is exactly why mixing damage rarely gets diagnosed as mixing damage.<\/p>\n<h2>The compatibility chart (simplified)<\/h2>\n<table>\n<tr>\n<th><\/th>\n<th>Lithium<\/th>\n<th>Lithium complex<\/th>\n<th>Polyurea<\/th>\n<th>Calcium<\/th>\n<th>Calcium complex<\/th>\n<th>Al complex<\/th>\n<\/tr>\n<tr>\n<td>Lithium<\/td>\n<td>OK<\/td>\n<td>OK<\/td>\n<td>Caution<\/td>\n<td>OK<\/td>\n<td>OK<\/td>\n<td>Caution<\/td>\n<\/tr>\n<tr>\n<td>Polyurea<\/td>\n<td>Check<\/td>\n<td>Check<\/td>\n<td>OK<\/td>\n<td>Check<\/td>\n<td>Check<\/td>\n<td>Check<\/td>\n<\/tr>\n<tr>\n<td>Calcium<\/td>\n<td>OK<\/td>\n<td>OK<\/td>\n<td>Check<\/td>\n<td>OK<\/td>\n<td>OK<\/td>\n<td>Caution<\/td>\n<\/tr>\n<tr>\n<td>Al complex<\/td>\n<td>Caution<\/td>\n<td>Caution<\/td>\n<td>Check<\/td>\n<td>Caution<\/td>\n<td>Caution<\/td>\n<td>OK<\/td>\n<\/tr>\n<\/table>\n<p><em>&#8220;Caution&#8221; = test before committing; failing pairs exist within these families. &#8220;Check&#8221; here means &#8220;check with the manufacturer&#8221; &#8211; do not assume.<\/em><\/p>\n<h2>Field rules that prevent 90% of failures<\/h2>\n<ol>\n<li><strong>Same thickener + same base oil family = usually safe.<\/strong> Still verify EP additives don&#8217;t clash (e.g., some moly and some overbased sulfonates interact).<\/li>\n<li><strong>Unknown history = purge, don&#8217;t top up.<\/strong> Relubricate at short intervals 3-4 times to push the old charge out before resuming normal intervals.<\/li>\n<li><strong>Colour and texture mean nothing.<\/strong> Two red greases can be lithium and polyurea.<\/li>\n<li><strong>When in doubt, ask for the compatibility statement.<\/strong> We issue written compatibility guidance for our grades against all major competitors&#8217; products.<\/li>\n<\/ol>\n<h2>What if the mix already happened?<\/h2>\n<p>Signs to watch: grease leaking from seals that never leaked before, bearing temperature up 10-15 &deg;C with no load change, or discoloured soft grease at the relief port. Response: stop relubricating with the new product, purge with the original grease at 2-3x normal quantity over several sessions, and inspect the bearing at the next window.<\/p>\n<p>Our technical team handles mixing incidents weekly. Send us photos of the grease in the bearing and the product labels involved, and we will tell you whether you have a problem and how to purge it.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Incompatible thickeners can turn your bearing cavity into a blocked, oily mess.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-9","post","type-post","status-publish","format-standard","hentry","category-technical"],"_links":{"self":[{"href":"https:\/\/llfgrease.com\/news\/wp-json\/wp\/v2\/posts\/9","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/llfgrease.com\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/llfgrease.com\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/llfgrease.com\/news\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/llfgrease.com\/news\/wp-json\/wp\/v2\/comments?post=9"}],"version-history":[{"count":0,"href":"https:\/\/llfgrease.com\/news\/wp-json\/wp\/v2\/posts\/9\/revisions"}],"wp:attachment":[{"href":"https:\/\/llfgrease.com\/news\/wp-json\/wp\/v2\/media?parent=9"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/llfgrease.com\/news\/wp-json\/wp\/v2\/categories?post=9"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/llfgrease.com\/news\/wp-json\/wp\/v2\/tags?post=9"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}