{"id":175618,"date":"2025-11-02T12:00:00","date_gmt":"2025-11-02T09:00:00","guid":{"rendered":"https:\/\/bukvaved.top\/v-chjom-raznica-mezhdu-maslami-5w40-i-10w40\/"},"modified":"2026-10-28T14:33:26","modified_gmt":"2026-10-28T11:33:26","slug":"what-is-the-difference-between-5w40-and-10w40-oils","status":"publish","type":"post","link":"https:\/\/bukvaved.top\/en\/v-chjom-raznica-mezhdu-maslami-5w40-i-10w40\/","title":{"rendered":"What is the difference between 5w40 and 10w40 oils?"},"content":{"rendered":"<p><strong>5W-40 oil differs from 10W-40 only in its low temperature performance: 5W-40 is thinner at low temperatures and, according to the SAE J300 standard, provides starting and pumpability at lower temperatures than <a href=\"https:\/\/avtomancar.com\/hado-10w-40\/\" target=\"_blank\" rel=\"noopener\">10W-40<\/a>.<\/strong> At engine operating temperature, both oils belong to the same viscosity grade, SAE 40, so in this respect they are equivalent. Oil selection is primarily determined by the vehicle manufacturer&#039;s recommendations.<\/p>\n<p>To sum it up<\/p>\n<ul>\n<li><strong>First digit (5W or 10W)<\/strong> Describes the oil&#039;s behavior when cold - the lower the number, the better the oil&#039;s fluidity during cold starts.<\/li>\n<li><strong>The second number (40)<\/strong> are the same, so at operating temperature both oils have viscosity in the same range.<\/li>\n<li>Cold start requirements according to SAE J300 standard: 5W \u2013 up to -30\u00b0C, 10W \u2013 up to -25\u00b0C (CCS viscosity); pumpability: 5W \u2013 up to -35\u00b0C, 10W \u2013 up to -30\u00b0C.<\/li>\n<li>The type of base (synthetic, semi-synthetic) and quality standards (ACEA, API, manufacturer standards) are not determined by the viscosity marking - they must be checked on the label.<\/li>\n<\/ul>\n<h2>What do the 5W-40 and 10W-40 symbols mean?<\/h2>\n<p>The viscosity of motor oils is determined by the standard <strong>SAE J300<\/strong> . 5W-40 and 10W-40 oils are all-season \u2013 they meet the requirements of both winter and summer classes.<\/p>\n<ul>\n<li><strong>Number with the letter W<\/strong> (meaning &quot;\u00ab <em>winter&quot;\u00bb<\/em> ) indicates the winter rating. It indicates the maximum viscosity during cold starts and the temperature at which oil can still be pumped to the lubrication points.<\/li>\n<li><strong>Number after the hyphen<\/strong> denotes the high-temperature viscosity grade. For grade 40, the kinematic viscosity at 100\u00b0C should be in the range of 12.5 to 16.3 mm\u00b2\/s, while the HTHS viscosity (measured at 150\u00b0C under high-shear conditions) for 5W-40 and 10W-40 oils should be at least 3.5 mPa s.<\/li>\n<\/ul>\n<p>The common misconception that the &quot;5W&quot; designation means the oil is thinner in all situations is incorrect. 5W-40 oil is thinner only when cold; once the engine warms up, both oils are considered the same grade.<\/p>\n<h2>The difference between 5W-40 and 10W-40 at cold start<\/h2>\n<p>Most engine wear occurs in the first moments after starting, before the oil reaches all components. The thinner the oil when cold, the faster the pump will distribute it throughout the engine and the easier it will be for the starter to turn the crankshaft.<\/p>\n<p>The SAE J300 standard sets limits for both classes:<\/p>\n<ul>\n<li><strong>5W<\/strong> \u2013 initial viscosity (CCS) max. 6600 mPa s at <strong>-30\u00b0C<\/strong> , the pumpability limit is estimated at <strong>-35\u00b0C<\/strong> .<\/li>\n<li><strong>10W<\/strong> \u2013 initial viscosity max. 7000 mPa s at <strong>-25\u00b0C<\/strong> , the pumpability limit is estimated at <strong>-30\u00b0C<\/strong> .<\/li>\n<\/ul>\n<p>In practice, this means that 5W-40 oil provides a margin of safety on frosty mornings. In the Polish climate, at typical winter temperatures, both oils ensure smooth engine starting, but for short trips and frequent cold starts, a lower winter grade oil is preferable.<\/p>\n<h2>Is 5W-40 oil synthetic and 10W-40 semi-synthetic?<\/h2>\n<p>On the market, 5W-40 oils are most often synthetic, while 10W-40 oils are often semi-synthetic or mineral. However, this <strong>market trend, not a rule<\/strong> . The SAE designation indicates viscosity only, not the base oil type or additive package quality. There are 10W-40 synthetic oils and 5W-40 semi-synthetic oils.<\/p>\n<p>For the same reason, the viscosity rating alone does not indicate the oil change interval. The interval is set by the vehicle manufacturer, and the oil quality is determined <strong>ACEA and API standards, as well as manufacturer approvals<\/strong> (e.g. VW, MB, BMW). A 5W-40 oil without the necessary approval may be a worse choice than a 10W-40 oil that does.<\/p>\n<h2>Comparison Chart: 5W-40 vs. 10W-40<\/h2>\n<table>\n<tbody>\n<tr>\n<th>Characteristic<\/th>\n<th>5W-40<\/th>\n<th>10W-40<\/th>\n<\/tr>\n<\/tbody>\n<tbody>\n<tr>\n<td><strong>SAE Winter Class<\/strong><\/td>\n<td>5 W<\/td>\n<td>10 W<\/td>\n<\/tr>\n<tr>\n<td><strong>Initial viscosity (CCS), max.<\/strong><\/td>\n<td>6600 mPa s at \u221230\u00b0C<\/td>\n<td>7000 mPa s at \u221225\u00b0C<\/td>\n<\/tr>\n<tr>\n<td><strong>Pumpability test temperature<\/strong><\/td>\n<td>-35\u00b0C<\/td>\n<td>-30\u00b0C<\/td>\n<\/tr>\n<tr>\n<td><strong>Viscosity at 100 \u00b0C<\/strong><\/td>\n<td>12.5\u201316.3 mm\u00b2\/s (class 40)<\/td>\n<td>12.5\u201316.3 mm\u00b2\/s (class 40)<\/td>\n<\/tr>\n<tr>\n<td><strong>HTHS at 150\u00b0C, min.<\/strong><\/td>\n<td>3.5 mPa s<\/td>\n<td>3.5 mPa s<\/td>\n<\/tr>\n<tr>\n<td><strong>Typical market base<\/strong><\/td>\n<td>Most often synthetic<\/td>\n<td>Often semi-synthetic or mineral<\/td>\n<\/tr>\n<tr>\n<td><strong>Price<\/strong><\/td>\n<td>Typically higher content (mainly due to base and additives).<\/td>\n<td>Usually lower<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>5W-40 or 10W-40 \u2013 which oil to choose?<\/h2>\n<p>First, check out <strong>with the operating manual or manufacturer&#039;s specifications<\/strong> . They will specify acceptable viscosity grades (often based on ambient temperature) and required quality standards. If the manual allows both types of oils, you can follow these recommendations:<\/p>\n<ul>\n<li><strong>5W-40<\/strong> \u2013 If your car is parked outside in winter, you mostly drive short distances around town, or you need better protection during cold engine starts.<\/li>\n<li><strong>10W-40<\/strong> \u2013 if the manufacturer recommends it (often for older engines), the vehicle is operated primarily at moderate temperatures, and the oil meets the required standards.<\/li>\n<li><strong>Changing 10W-40 oil to 5W-40<\/strong> It is generally safe because the wear resistance class is the same for hot conditions and better for winter conditions, provided that the oil meets the standards set by the manufacturer.<\/li>\n<li><strong>Changing 5W-40 oil to 10W-40<\/strong> It only makes sense if the manufacturer allows the use of 10W class oil in a given climate zone.<\/li>\n<\/ul>\n<p>Engines with diesel particulate filters often require oils with reduced sulfated ash content (e.g., ACEA C standards). Viscosity alone isn&#039;t enough \u2013 always compare the specifications on the label with the manufacturer&#039;s requirements. If in doubt, contact a service center.<\/p>\n<h2>Frequently Asked Questions (FAQ)<\/h2>\n<p><strong>What is the difference between 5W-40 and 10W-40 oils?<\/strong><\/p>\n<p>For winter use only. 5W-40 oil has better fluidity at low temperatures (SAE J300 requirements for starting at -30\u00b0C instead of -25\u00b0C). At operating temperature, both oils have the same viscosity grade, SAE 40.<\/p>\n<p><strong>Can I use 5W-40 oil instead of 10W-40?<\/strong><\/p>\n<p>Generally, yes \u2013 in the hot-climate class, everything is the same, and in the winter class, it&#039;s better. This is achieved by meeting the quality standards (ACEA, API, certifications) set by the vehicle manufacturer.<\/p>\n<p><strong>Can you mix 5W-40 oil with 10W-40 oil?<\/strong><\/p>\n<p>Motor oils generally mix well, but the resulting mixture has intermediate parameters and doesn&#039;t always meet required standards. It&#039;s best to use the same oil that&#039;s already in the engine and consider mixing as a backup until the next oil change.<\/p>\n<p><strong>Which oil is better for winter: 5W-40 or 10W-40?<\/strong><\/p>\n<p>In winter, 5W-40 oil has an advantage because it is less fluid at low temperatures and reaches engine components faster after starting.<\/p>\n<p><strong>Is 10W-40 oil thicker than 5W-40?<\/strong><\/p>\n<p>For cold use only. Once the engine is warm, both oils share the same viscosity grade, SAE 40.<\/p>\n<h2>See also<\/h2>\n<ul>\n<li>What is the difference between 5w30 and 5w40 oils?<\/li>\n<li>What is the difference between synthetic and semi-synthetic oil?<\/li>\n<li>What is the difference between 75w80 and 75w90 oils?<\/li>\n<li>What is the difference between 2T and 4T oil?<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>5W-40 oil differs from 10W-40 only in its characteristics at low temperatures: 5W-40 is more liquid at low temperatures and, according to the standard<\/p>","protected":false},"author":1,"featured_media":175619,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[67,20],"tags":[70],"class_list":["post-175618","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-vopros-otvet","category-fakty","tag-chem-otlichaetsya"],"_links":{"self":[{"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/posts\/175618","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/comments?post=175618"}],"version-history":[{"count":2,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/posts\/175618\/revisions"}],"predecessor-version":[{"id":175725,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/posts\/175618\/revisions\/175725"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/media\/175619"}],"wp:attachment":[{"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/media?parent=175618"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/categories?post=175618"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bukvaved.top\/en\/wp-json\/wp\/v2\/tags?post=175618"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}