{"product_id":"penn-grade1-classic-gl-4-gear-oil-sae-80w-90-1-qt-2-pack-mineral-gl-4-for-brass-syncros","title":"PENN GRADE1 Classic GL-4 Gear Oil SAE 80W-90, 1 Qt (2-Pack) — Mineral GL-4 for Brass\/Syncros","description":"\u003cp\u003e\u003cstrong\u003ePENN GRADE1 Classic Multi-Purpose GL-4 Gear Oil SAE 80W-90 is a mineral-based gear lubricant formulated for older manual transmissions and transaxles that use yellow metallurgy and synchronizers.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eThis dual-quart pack delivers a purpose-built GL-4 formulation designed to protect brass, bronze and other soft metal components commonly found in classic and vintage manual gearboxes. The blend uses premium mineral base stocks and select additives to maintain synchronizer feel and protect bushings, thrust washers and gears without adding friction modifiers that can interfere with shifting. It’s not intended for limited-slip differentials or applications requiring GL-5 extreme-pressure fluids, or where an OEM-specific fluid is required.\u003c\/p\u003e\n\n\u003ch3\u003eWhy choose GL-4 80W-90 for older manual transmissions?\u003c\/h3\u003e\n\u003cp\u003ePENN GRADE1 GL-4 80W-90 is engineered to match the metallurgy and synchronizer systems of many classic vehicles. It provides film strength and corrosion protection while avoiding additives that can harm brass synchronizers. The result is consistent shifting performance with protection for soft-metal components.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eFormulated for yellow metallurgy (brass, bronze, copper).\u003c\/li\u003e\n  \u003cli\u003eContains no friction modifiers that impede synchronizers.\u003c\/li\u003e\n  \u003cli\u003ePremium mineral base stocks for stable viscosity.\u003c\/li\u003e\n  \u003cli\u003eHelps protect bushings, thrust washers and synchronizers.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow does this oil affect shifting and synchronizer life?\u003c\/h3\u003e\n\u003cp\u003eBecause it omits friction modifiers and follows GL-4 additive chemistry, this gear oil helps maintain predictable synchronizer engagement and shift quality. It minimizes sticking or grabbing that can arise from incompatible additives, helping preserve the intended feel of manual transmissions.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eClean, consistent synchronizer engagement.\u003c\/li\u003e\n  \u003cli\u003eReduced risk of synchro wear from incompatible friction agents.\u003c\/li\u003e\n  \u003cli\u003eStable viscosity across operating temperatures for reliable shifts.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eIs this product suitable for all driveline components?\u003c\/h3\u003e\n\u003cp\u003eThis GL-4 80W-90 is ideal for manual transmissions and transaxles that specify GL-4. It is not formulated for GL-5 requirements or limited-slip differentials and should not replace OEM-specified specialized fluids where required.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eUse in classic manual transmissions and transaxles.\u003c\/li\u003e\n  \u003cli\u003eNot for GL-5-only applications or EP-heavy requirements.\u003c\/li\u003e\n  \u003cli\u003eAvoid in limited-slip units that require friction-modified oils.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow should I use and store these quart bottles?\u003c\/h3\u003e\n\u003cp\u003eThe product comes in two one-quart bottles for convenient service intervals or to keep a spare on hand. Store in a cool, dry place away from direct sunlight and contaminate-free. Follow vehicle manufacturer fill capacities and change intervals for best results.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eTwo 1-quart bottles—easy to carry and pour.\u003c\/li\u003e\n  \u003cli\u003eKeep sealed until use; store in cool, dry area.\u003c\/li\u003e\n  \u003cli\u003eObserve vehicle-specific fill amounts and change schedules.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho is this for? PENN GRADE1 Classic GL-4 80W-90 is aimed at owners, restorers, and mechanics working on classic cars, trucks and vintage manual-transmission vehicles that use brass or bronze synchronizers and soft-metal components. If your vehicle’s service manual calls for a GL-4 80W-90 or you want a mineral-based option that preserves original shifting feel, this product is a practical choice. Avoid it if your drivetrain explicitly requires GL-5, limited-slip additives, or a manufacturer-prescribed synthetic specification.\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: Can I use this in a limited-slip differential?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: No. This GL-4 oil does not contain limited-slip friction modifiers and is not recommended for limited-slip differentials.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Is PENN GRADE1 80W-90 suitable for modern synthetic-requiring gearboxes?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Generally no. It’s a mineral-based GL-4 formulation and shouldn’t replace OEM-mandated synthetic or GL-5 fluids.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"PENN GRADE1","offers":[{"title":"Default Title","offer_id":48086183641246,"sku":"B0CHG54RGN","price":43.98,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0781\/2041\/9486\/files\/penn-grade1-front-packaging_fd2aa2f2-d112-4fda-ac76-1f47929b7117.jpg?v=1785888883","url":"https:\/\/northtrailauto.ca\/products\/penn-grade1-classic-gl-4-gear-oil-sae-80w-90-1-qt-2-pack-mineral-gl-4-for-brass-syncros","provider":"North Trail Auto","version":"1.0","type":"link"}