{"product_id":"mt-90-75w-90-gl-4-synthetic-gear-oil-4-quart-smooth-cold-shift","title":"MT-90 75W-90 GL-4 Synthetic Gear Oil 4 Quart - Smooth, Cold-Shift","description":"\u003cp\u003eIn this review the MT-90 75W-90 GL-4 synthetic gear oil is evaluated for drivers who want reliable manual transmission performance and longer synchronizer life. The bottom line: this lubricant is best for owners of manual transmissions and transaxles who need a GL-4 fluid that eliminates notchy shifting and protects brass synchronizers without the reactive sulfurs found in harsher gear oils. It stands out for delivering quicker, more consistent shifts even when cold and for meeting a wide range of viscosity requirements, making it a practical single-bottle solution for many transmissions.\u003c\/p\u003e\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBalanced slipperiness:\u003c\/strong\u003e Provides a perfect synchronizer coefficient of friction for smoother, more precise shifts and reduced notchy feel.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCold performance:\u003c\/strong\u003e Maintains excellent shifting when cold, so daily driving and cold starts benefit from quicker gear engagement.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSafe for brass synchronizers:\u003c\/strong\u003e Lacks the reactive sulfurs present in many GL-5 oils, preventing corrosion and wear on non-ferrous synchros.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBroad viscosity coverage:\u003c\/strong\u003e Satisfies gear oil viscosity requirements equivalent to 75W, 80W, SAE 40 and some 10W40\/15W40 engine oils for flexible application.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHigh-temperature protection:\u003c\/strong\u003e Reduces gear whine and rattle at higher operating temperatures and extends gear life under load.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatibility:\u003c\/strong\u003e Works with petroleum and other synthetic lubricants, easing fluid changes and top-offs.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eWho It's For\u003c\/h2\u003e\n\u003cp\u003eThe MT-90 75W-90 GL-4 is aimed at drivers with manual transmissions and transaxles who want improved shift quality, longer synchronizer life, and a lubricant that is non-corrosive toward brass synchros. It is especially useful for enthusiasts who demand smoother downshifts and reduced gear noise at high temperatures.\u003c\/p\u003e\n\u003cp\u003eIt is not intended for differentials requiring GL-5 or other sulfur-phosphorus extreme-pressure additives; those applications require oils specified for GL-5 duty. Also, those looking specifically for engine oil should choose a dedicated motor oil rather than this gear-focused lubricant.\u003c\/p\u003e\n\u003ch2\u003ePros \u0026amp; Cons\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003ePros\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eEliminates notchy shifting and enables quicker, more consistent shifts for a better driving experience.\u003c\/li\u003e\n\u003cli\u003eSafe for brass synchronizers because it lacks reactive sulfurs, helping prevent corrosion and premature wear.\u003c\/li\u003e\n\u003cli\u003eWide viscosity compatibility reduces the need for multiple specialty fluids and suits a range of transmission conditions.\u003c\/li\u003e\n\u003cli\u003ePerforms well when cold and reduces gear noise at higher temperatures, useful for varied climates and spirited driving.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eCons\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eNot suitable for applications that explicitly require GL-5 or extreme-pressure gear oils, so verify your vehicle's spec before use.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eSpecifications\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctr\u003e\n\u003ctd\u003eProduct\u003c\/td\u003e\n\u003ctd\u003eMT-90 Manual Transmission Lubricant\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eViscosity\u003c\/td\u003e\n\u003ctd\u003e75W-90 (meets SAE 10W\/15W\/40 engine oil viscosity equivalents)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePerformance Rating\u003c\/td\u003e\n\u003ctd\u003eGL-4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eVolume\u003c\/td\u003e\n\u003ctd\u003e4 quart\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatibility\u003c\/td\u003e\n\u003ctd\u003eSafe with petroleum and other synthetic lubricants\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSynchronizer Safety\u003c\/td\u003e\n\u003ctd\u003eNon-corrosive toward brass synchronizers (no reactive sulfurs)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\u003ch2\u003eOur Verdict\u003c\/h2\u003e\n\u003cp\u003eThe MT-90 75W-90 GL-4 synthetic gear oil is a solid choice for manual transmission owners who prioritize smooth shifting and synchronizer longevity. Its balanced slipperiness and cold-shift performance make it good value for drivers replacing or topping off transmission fluid, provided the vehicle requires a GL-4 or motor-oil-equivalent lubricant rather than a GL-5 product.\u003c\/p\u003e\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eCan this oil be used in a differential?\u003c\/strong\u003e\u003cbr\u003eThis product is formulated as a GL-4 gear oil for manual transmissions and transaxles; use only if the differential specifies GL-4 or a compatible viscosity-do not use where GL-5 is required.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs it safe for synchronizers made of brass?\u003c\/strong\u003e\u003cbr\u003eYes. The formula lacks the reactive sulfurs found in many GL-5 oils and is non-corrosive toward brass synchronizers.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill it mix with my existing synthetic or petroleum gear oil?\u003c\/strong\u003e\u003cbr\u003eYes. The MT-90 is compatible with petroleum and other synthetic lubricants, which helps when topping off or changing fluids.\u003c\/p\u003e","brand":"Red Line","offers":[{"title":"Default Title","offer_id":48240962207963,"sku":"B005F1ZH7U","price":92.4,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0724\/1043\/1707\/files\/413K_VuOJML._AC_SY300_SX300.jpg?v=1776284363","url":"https:\/\/gearmusthave.com\/products\/mt-90-75w-90-gl-4-synthetic-gear-oil-4-quart-smooth-cold-shift","provider":"GearMustHave","version":"1.0","type":"link"}