Tuesday, June 07, 2005
Ready Reference for Lubricant and Fuel Performance: "
Ready Reference for Lubricant and Fuel Performance
Driveline Lubricants - Automotive Gear Lubricants
API Gear Oil Designations (See API Publication 1560 for full description)
Service Designations in Current Use
- GL-1 Denotes lubricants intended for manual transmissions operating under such mild conditions that straight petroleum or refined petroleum oil may be used satisfactorily. Oxidation and rust inhibitors, defoamers and pour depressants may be added to improve the characteristics of these lubricants. Friction modifiers and extreme pressure additives shall not be used.
- GL-4 Denotes lubricants intended for axles with spiral bevel gears operating under moderate to severe conditions of speed and load or axles with hypoid gears operating under moderate speeds and loads. These oils may be used in selected manual transmissions and transaxle applications where API MT-1 lubricants are unsuitable.
- GL-5 Denotes lubricants intended for gears, particularly hypoid gears, in axles operating under various combinations of high-speed shock loads and low-speed, high-torque conditions. Lubricants qualified under MIL-L-2105D satisfy the requirements of the API GL-5 specification, although the API designation does not require military approval.
- MT-1 Denotes lubricants intended for nonsynchronized manual transmissions used in buses and heavy-duty trucks. Lubricants meeting the requirements of API MT-1 provide protection against the combination of thermal degradation, component wear and oil seal deterioration. API MT-1 does not address the performance requirements of synchronized transmissions and transaxles in passenger car and heavy-duty applications.
Service Designations not in Current Use
- GL-2 Denotes lubricants intended for automotive worm gear axles operating under such conditions of load, temperature and sliding velocity that lubricants satisfying API GL-1 service will not suffice. Products suited for this type of service contain antiwear additives or film-strength improves specifically designed to protect worm gears.
- GL-3 Denotes lubricants intended for manual transmissions operating under moderate to severe conditions and spiral-bevel axles operating under mild to moderate conditions of speed and load. These service conditions require lubricants having good load-carrying capacities, exceeding those satisfying API GL-1 service but below the requirements of lubricants satisfying API GL-4 service. Lubricants designated for API GL-3 service are not intended for axles with hypoid gears.
- GL-6 Denotes lubricants intended for gears designed with very high pinion offsets. Such designs typically require protection from gear scoring in excess of that provided by API GL-5 gear oils. A shift to more modest pinion offsets and the obsolescence of original API GL-6 test equipment and procedures have greatly reduced the commercial use of these lubricants.
BenzWorld : Viewing a thread: "RE: Whats the importance of Non-Hypoid gear oil?
I had saved this information, this guy is so thorough that it needs no more explanations:
From: firstname.lastname@example.org (Andy Dingley)
Subject: Re: Hypoid vs. Non-Hypoid
Date: Tue, 09 Jan 1996 17:45:49 GMT
Mark <74551.2327@CompuServe.COM> wrote:
>Can someone explain the difference between Hypoid and Non-Hypoid oil?
'Hypoid' is not really a question of oil, so much as a question of gearcutting. Old (1920's) rear axles used straight bevel gears to form the crownwheel and pinion. These had two disadvantage, the pinion shaft meets the crownwheel on its central axis, and the straight cut gears are noisy. By using a more complex 'hypoid' gear tooth shape (if you look at a pinion, the teeth appear twisted) these problems can be addressed. The more gradual engagement of the teeth along their length reduces noise. By careful design of the geometry the pinion can be made to mesh _below_ the axis of the crownwheel. As the centre height of the crownwheel is fixed by the wheel height, this allows the propshaft to be lowered relative to the car body, giving a clearer floorpan and lower centre of gravity for better cornering. Hypoid bevels are now universal in this application. Because of the sliding contact that hypoid gears make, their hydrodynamic contact pressure is higher. To be suitable for use with hypoid gears, a lubricant must be capable of resisting high pressures. Oils with 'EP' ratings (Extreme Pressure) such as EP90 are required. Some brands describe themselves as 'hypoid' instead, a term which is synonymous with EP. GL-5 is a formal API standard for this type of oil (comparable to MIL-L-2105B/C/D)
Pennzoil Frequently Asked Questions: "2. What happens if API GL-5 gear oil is used in an API GL-4 gear oil application?
API GL-4 and API GL-5 products typically use the same extreme pressure (EP) additive system, with the API GL-5 having about twice the concentration of a API GL-4. In service, these additives become active under extreme load and temperature when the protective oil film can be squeezed away. EP additives work by forming wear-resistant compounds with the metal of the gear tooth surface. As the gears mesh, these compounds shield the gear teeth from direct metal-to-metal contact that would cause wear and damage to the gears. If too little of the active additive is present, proper protection would be compromised. Too much of this additive could cause excessive chemical corrosion of the gear surface. If an API GL-5 gear oil is used in a application where API GL-4 gear oil is called for, chemical corrosion of 'yellow metal' components may occur, such as bronze synchronizers, brass bushings, etc. This may lead to shifting difficulties or shortened equipment life. "