{"product_id":"red-line-mt-90-75w-90-gl-4-manual-transmission-lubricant-1-quart-4-pack-smooth-shifting-synchro-protection","title":"Red Line MT-90 75W-90 GL-4 Manual Transmission Lubricant — 1 Quart (4 Pack), Smooth Shifting \u0026 Synchro Protection","description":"\u003cp\u003e\u003cstrong\u003eRed Line MT-90 75W-90 GL-4 is a high-performance manual transmission and transaxle lubricant formulated for smooth shifting, extended synchronizer life, and safe use with brass synchros.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eEngineered for manual gearboxes and transaxles that call for GL-1, GL-3, or GL-4 fluids, Red Line MT-90 provides a balanced friction profile that reduces notchy shifts and preserves synchronizers without the reactive sulfurs found in many GL-5 oils. It’s designed for drivers and technicians who want dependable gear protection, consistent shifting in a range of temperatures, and compatibility where GL-4 specifications are required.\u003c\/p\u003e\n\n\u003ch3\u003eHow does MT-90 improve shifting performance?\u003c\/h3\u003e\n\u003cp\u003eMT-90 is blended to deliver the proper synchronizer coefficient of friction so shifts are smooth and predictable, even during cold starts. That reduces grinding and hesitation and helps maintain the original shift quality of the transmission.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eOptimized friction for quicker, cleaner shifts\u003c\/li\u003e\n  \u003cli\u003eFormulated to avoid notchy or sticky shifting when cold\u003c\/li\u003e\n  \u003cli\u003eHelps protect synchronizers and shift forks from premature wear\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWill this product protect gears and synchronizers?\u003c\/h3\u003e\n\u003cp\u003eThis GL-4-rated lubricant offers strong gear protection and is safer for brass or bronze synchronizers because it avoids the corrosive reactive sulfurs found in GL-5 formulations. Regular use helps preserve synchro life and reduces metal wear in sliding and hypoid gear components where GL-4 is specified.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eReduces gear wear under normal and severe driving\u003c\/li\u003e\n  \u003cli\u003eSafe for brass\/bronze synchronizers and common synchromesh systems\u003c\/li\u003e\n  \u003cli\u003eRecommended where GL-1, GL-3, or GL-4 specifications apply\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhich viscosities and applications does MT-90 support?\u003c\/h3\u003e\n\u003cp\u003eMT-90 is a 75W-90 viscosity oil suitable for many manual transmissions, transaxles, and differentials that call for 75W, 80W, SAE 40, 10W-40, or 15W-40 gear or motor oils. Check your vehicle’s service manual to confirm compatibility, particularly for systems specifying GL-4 gear oils or special synchromesh fluids.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eViscosity: 75W-90 for a broad temperature range\u003c\/li\u003e\n  \u003cli\u003eWorks where special synchromesh fluids are required\u003c\/li\u003e\n  \u003cli\u003eCompatible with applications calling for GL-1, GL-3, and GL-4\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow should I use this 1-quart pack for maintenance?\u003c\/h3\u003e\n\u003cp\u003eThe 1-quart size is convenient for top-ups, partial fills, or servicing multiple small gearboxes. For full replacements consult capacity specs; many differentials and boxes require more than one quart, but this packaging makes it simple to add precise amounts during service.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e1-quart bottles are ideal for precise top-ups and pilot refills\u003c\/li\u003e\n  \u003cli\u003eBuy a multi-pack (4 pack) for servicing several gearboxes or full fills\u003c\/li\u003e\n  \u003cli\u003eStore tightly capped, out of direct sunlight, at moderate temperature\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho is this for? Red Line MT-90 75W-90 GL-4 MTL suits mechanics, DIY enthusiasts, and fleet operators who need a reliable manual transmission lubricant that preserves synchronizer function while protecting gears under varied driving conditions. It’s especially useful where manufacturers specify GL-4 or special synchromesh fluids and where brass or bronze synchronizers must be protected. If your vehicle’s service manual lists 75W-90 or GL-4 gear oil, MT-90 is a strong candidate to maintain shift quality and component longevity without introducing reactive sulfurs common in some other gear oils.\u003c\/p\u003e\n\u003csection class=\"product-faq-snippet\"\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Is MT-90 safe for brass synchronizers?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes. MT-90 lacks the reactive sulfurs in many GL-5 oils and is safe for brass\/bronze synchros.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Can I use MT-90 for cold-weather shifting?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes. The 75W-90 formulation improves cold-shift performance and reduces notchy shifting.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"Red Line","offers":[{"title":"Default Title","offer_id":48081463443614,"sku":"B000QFN326","price":113.89,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0781\/2041\/9486\/files\/red-line-mt90-front-packaging.jpg?v=1785805723","url":"https:\/\/northtrailauto.ca\/products\/red-line-mt-90-75w-90-gl-4-manual-transmission-lubricant-1-quart-4-pack-smooth-shifting-synchro-protection","provider":"North Trail Auto","version":"1.0","type":"link"}