Is it possible to fill the box with engine oil?
Engine oil in automatic transmission
It is even difficult to imagine why a car owner in his right mind would fill in an expensive automatic transmission with a basically unsuitable gear oil, not to mention engine oil. Let's discuss in theory what the use of motor lubricants in automatic transmissions is fraught with.
Lubricants for automatic transmissions (so-called ATF fluids) are actually closer in their properties to hydraulic oils than to engine oils. Therefore, if there was a question about using a "spindle" or other hydraulic oil in the machine, one could think of some kind of interchangeability here.
Engine oil is quite different from ATF fluids.
- Inappropriate temperature setting. Fluids for automatic transmissions, even in severe frosts, retain acceptable fluidity relative to motor oils. Relatively speaking, if the oil thickens to a consistency, for example, honey, then the hydraulics (starting from the torque converter, pumping with a hydraulic plate) will be partially or completely paralyzed. Although there are winter oils that remain quite liquid even at very low temperatures (0W standard). So this point is very conditional.
- Unpredictable performance under high pressures. One of the prerequisites for the normal operation of the automatic transmission is the predictability of the behavior of the oil under pressure. Automatic transmission is a complex mechanism consisting of an extensive system of hydraulic channels. Each channel has its own, strictly normalized, values of pressure and flow velocity. The fluid must not only be incompressible and transmit force well, but in no case should it form air pockets.
- Inappropriate additive package that will harm the box. The only question is how long it will take to see the effects. The mechanical part in the automatic transmission works with high contact loads, which engine oil at its peak cannot cope with. Scuffing and chipping of teeth is a matter of time. And rich engine oil additives, which are designed for 10-15 thousand kilometers in the engine (and in completely different conditions than in automatic transmissions), can precipitate. Deposits in the valve body will certainly cause problems.
In general, pouring engine oil into an automatic transmission is possible only as a sophisticated and expensive experiment: how long will the automatic transmission last on engine oil. For normal operation, even the most expensive and technologically advanced engine oil will not work in an automatic transmission.
Engine oil in manual transmission
We note right away that engine oil can be poured into the box of VAZ cars of classic models. This was written even in the factory instructions for early models.
On the one hand, such a decision was based on the lack of good gear oils in the 80s, when the mass production of Zhiguli began. Lubricants like TAD-17 had an increased viscosity, which was acceptable for trucks. But in conjunction with the low-power engines of the first VAZ models, a large percentage of the power, especially in winter, went to viscous friction in the box. And this caused operational problems with the car in the winter, such as increased fuel consumption, low throttle response during acceleration and a drop in top speed.
In addition, the structural margin of safety for the manual transmission of VAZ cars was very high. Therefore, if engine oil reduced the resource of the box, it was not so much that it became a critical problem.
With the advent of more advanced oils, this item was removed from the instruction manual. However, the box has not undergone structural changes. Therefore, even now, it is possible to fill in engine oils in a box of VAZ classics. The main thing is to choose thicker lubricants, with a viscosity of at least 10W-40. It will also not be a big mistake if, in the absence of a suitable transmission lubricant, add a small amount of engine oil to the VAZ manual transmission.
It is impossible to pour engine oils into the mechanical boxes of modern cars. The loads on the gear teeth in them have increased significantly compared to cars produced 20-30 years ago. And if the main gear in the box is hypoid, and even with a significant displacement of the axles, the filling of engine oils in this case is completely prohibited. The point is the lack of a sufficient amount of extreme pressure additives, which will certainly lead to the destruction of the contact surface of the gear teeth of this type.
