{"product_id":"red-line-75w-90-gl-5-synthetic-gear-oil-quart-hypoid-limited-slip-friction-modified-protection","title":"RED LINE 75W-90 GL-5 Synthetic Gear Oil Quart — Hypoid Limited Slip, Friction-Modified Protection","description":"\u003cp\u003e\u003cstrong\u003eRed Line 57904 is a fully synthetic 75W-90 GL-5 hypoid gear oil formulated with friction modifiers to work in many clutch-type limited slip differentials while providing high-temperature protection and smooth gear action.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eThis gear oil is engineered for passenger cars, light trucks and performance vehicles that require a GL-5 specification and benefit from a synthetic formulation. With an SAE 75W-90 viscosity, it replaces many conventional 80W-90 and SAE 90 differentials and includes additives to reduce chatter in many limited slip systems. It is not intended for most manual transmissions or transaxles where synchromesh compatibility is critical.\u003c\/p\u003e\n\n\u003ch3\u003eWill this oil work in my limited slip differential?\u003c\/h3\u003e\n\u003cp\u003eYes — Red Line 57904 includes friction modifiers to suit a wide range of clutch-type limited slip differentials without adding aftermarket additives in most cases. Always check your vehicle manufacturer’s requirements and the differential maker’s guidance before switching oils.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eFormulated for clutch-type limited slip systems\u003c\/li\u003e\n  \u003cli\u003eFriction modifiers already blended — usually no extra additive needed\u003c\/li\u003e\n  \u003cli\u003eCompatible with many OEM LSDs when GL-5 is acceptable\u003c\/li\u003e\n  \u003cli\u003eConsult service manual for uncommon or proprietary LSDs\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow does the 75W-90 viscosity benefit performance and protection?\u003c\/h3\u003e\n\u003cp\u003eThe 75W-90 viscosity provides reliable film strength at high loads while offering easier cold-flow characteristics than straight SAE 90 oils. That balance helps reduce metal-to-metal contact under heavy hypoid loads and aids in smoother engagement in cooler climates.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eHigh-pressure protection for hypoid gears\u003c\/li\u003e\n  \u003cli\u003eBetter cold starting flow than SAE 90\u003c\/li\u003e\n  \u003cli\u003eMaintains viscosity at elevated operating temperatures\u003c\/li\u003e\n  \u003cli\u003eSuitable replacement for many 80W-90 or SAE 90 specs\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eIs this oil suitable for my transmission or transaxle?\u003c\/h3\u003e\n\u003cp\u003eNo — this product is optimized for differentials, not most manual transmissions or transaxles that rely on synchronizers. Its extreme slipperiness can interfere with synchronizer engagement and cause shifting problems in gearboxes designed for higher-friction oils.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eNot recommended for most synchromesh transmissions\u003c\/li\u003e\n  \u003cli\u003eAvoid use where manufacturer specifies gear oil formulated for transmissions\u003c\/li\u003e\n  \u003cli\u003eUse only in gear sets\/differentials calling for GL-5 or compatible specs\u003c\/li\u003e\n  \u003cli\u003eCheck OEM documentation if unsure\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat specifications and approvals does this product meet?\u003c\/h3\u003e\n\u003cp\u003eRed Line 57904 meets GL-5 performance standards and is formulated to exceed the demands of MIL-L-2105E and related specifications. It is a practical choice where manufacturers accept GL-5 oils and can serve as a direct replacement for many 80W-90 or SAE 90 differential recommendations.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eAPI GL-5 level performance\u003c\/li\u003e\n  \u003cli\u003eCompatible with GL-6 and MT-1 environments where GL-5 is permitted\u003c\/li\u003e\n  \u003cli\u003eMeets MIL-L-2105E and SAE J2360 targets\u003c\/li\u003e\n  \u003cli\u003eAcceptable alternative to Chrysler MS-9763 and similar specs\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho is this for? Red Line 57904 75W-90 is aimed at owners of passenger cars, light trucks, and performance or racing vehicles that require a GL-5 hypoid gear oil and want the benefits of a synthetic formulation with LSD compatibility. It suits mechanics and enthusiasts who need superior high-load protection and smoother operation in differentials, while those seeking a transmission oil for synchromesh gearboxes should choose a product specified for transmissions. Always verify recommended viscosity and spec with your vehicle manufacturer before use.\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 Red Line 57904 in a limited slip differential without extra additives?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Usually yes—this oil contains friction modifiers suitable for many clutch-type LSDs; check your differential manual for uncommon systems.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Is Red Line 75W-90 safe for manual transmissions?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: No—its slipperiness can impair synchronizers. Use transmission-specific oil where the manufacturer requires it.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"RED LINE","offers":[{"title":"Default Title","offer_id":48086191538334,"sku":"B000CPCBF0","price":41.72,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0781\/2041\/9486\/files\/red-line-57904-front-quart-packaging.jpg?v=1785889224","url":"https:\/\/northtrailauto.ca\/products\/red-line-75w-90-gl-5-synthetic-gear-oil-quart-hypoid-limited-slip-friction-modified-protection","provider":"North Trail Auto","version":"1.0","type":"link"}