Deciphering gear oil 75W-90
Content
Gear oils are classified according to the same standards as engine oils, but the list of main technical characteristics is somewhat different. We will discuss 75W-90 gear oil, typical characteristics, grades and classifications of oils from different manufacturers.
Specifications 75W-90
By analogy with the classification of motor oils, gear oils have a winter and summer index. In winter, the temperature is determined when the oil thickens and cannot normally pass to all parts during start-up. Summer indicates kinematic viscosity at operating temperature, that is, how easily the oil will pass through all channels and how thick the oil film will be. In boxes, as in engines, the space between the parts is different and each type of box needs its own viscosity.
Typical ratings for SAE 75W-90:
| Characterization | Index | transcribed |
|---|---|---|
| Kinematic viscosity at 100 ° C | 13,5-18,5 sSt | The indicator must be within these limits for the oil to be labeled 75W-90. |
| Freezing point | -40 | May differ. This indicator indicates the temperature at which the oil completely freezes and cannot pass through the channels. |
| Flash point | 210 | May vary +/- 10-15 degrees. |
Performance properties of oils according to API classification GL4, GL5
Oils can have the same SAE viscosity but differ in API. The difference in composition is no less important when choosing:
- GL-4 - for boxes with hypoid and bevel gears. Limited in temperature up to 150 degrees and in pressure up to 3000 MPa. In other words, for front wheel drive vehicles.
- GL-5 - for vehicles operating under shock load and high pressure - more than 3000 MPa. Suitable for bevel hypoid gears in gearboxes, main gears with drive axles.
It is important to choose exactly the class that is prescribed by the box manufacturer. For example, GL-4 contains less sulfur and phosphorus additives than GL-5. These additives are necessary to create a protective layer that protects against wear. This substance is stronger than copper, and if there are copper elements in the box, GL-5 brand oil will quickly destroy them.
Viscosity 75W-90 and 80W-90: what's the difference?
Kinematic viscosity will be about the same, but 75W is always slightly less viscous. They are frost-resistant, if 75W has a maximum temperature threshold at the edge of -40 degrees, then 80W has a maximum temperature of -26. That is, in a cold box there will be noticeable differences, but when heated, there will be no pronounced differences.
Can 75W-90 and 80W-90 be mixed
Under normal conditions, I will always say one thing: no, you can’t mix. Ideally, you should fill in oil of the same viscosity, grade and manufacturer. If there is no other way out, it is allowed to add 80W-90 oil to 75W-90 or vice versa, but select the required class, type of oil - synthetics, semi-synthetics or mineral water, and the manufacturer. This is ideal, but if there are no such conditions, we at least select the required class according to the API. After mixing, I recommend changing the lubricant as soon as possible.
Gear Oil Rating 75W-90
The Gear 300 model
Highly rated due to effective protection against a stalker - index 60,1. Optimal indicators of density and temperature, critically thickens at -60 degrees, which is not bad for 75W.
It is poured into sports car gearboxes, synchronized and non-synchronized manual transmissions, non-locking hypoid type axles operating at high load and low speed.
According to API, it belongs to the classes GL-4 and GL-5.
Castrol Syntrans Transaxle
Synthetic oil with optimum extreme pressure and antiwear properties, the composition includes a package of special additives. According to API GL-4+. Suitable for manual transmissions, block transmissions with final drive of the front drive axle, transfer cases and final drives. Loses fluidity at a slightly lower temperature than the previous one - 54 degrees below zero. Suitable for long term use.
Mobile Mobilube 1 SHC
Synthetic product with a complex of modern additives. Stable over a wide range of temperatures, high pressures and shock loads. The freezing threshold is the same: 54 degrees with a minus sign, which is not bad for 75W.
API GL-4 and GL-5 grades are suitable for heavy duty applications where extremely high pressure requirements are required. It can be poured into trucks and cars, minibuses, SUVs, construction and agricultural machinery. It has a list of approvals from transmission manufacturers.
Total Transmission SYN FE
Oil with good performance properties is poured into heavily loaded gears and drive axles, that is, in cases where a large load is placed on the transmission. Retains viscosity over a wide temperature range, protects and lubricates under severe operating conditions. Suitable for hypoid gears and synchronized shafts with manual transmissions. You can increase the replacement interval, there are a number of tolerances from box manufacturers.
LIQUI MOLY Hypoid Gear Oil TDL
According to API GL-4, GL-5 classes. Good test results, consumption at -40. Some other oil indicators are slightly above average relative to competitors, so it does not take first place.
Semi-synthetic, can be poured into different gearbox designs. In addition, it has a relatively low cost.
I SAY GF TOP
Korean synthetic. Retains fluidity at low temperatures, shows good results at high temperatures, which means it resists wear well. According to the reviews of car owners, with this oil the box works very quietly and smoothly even in cold weather. It can be used in manual transmissions, drive axles and units for which there are no additional manufacturer's requirements for the fluid used. Loses fluidity only at -45 degrees.
