It is the weight of the multi-vicosity oil. The 10 is the weight of the oil when cold. The W stands for Winter. The 40 is the weight of the oil when it gets hot.
no car has to have 10w40 its only choice 10w40 means that the oil can range from 10 weight to 40 weight so its only if you want to run a thicker oil like to cover up a knock or something like that Secondary Answer: The above is not really correct. 10w40 has the cold flow ability of a 10 weight oil and is a 40 weight oil at full temperature. This does not mean that it gets thicker as it gets warmer, that completely defies the laws of science. There are currently no new US market cars that require 10w40. 10w40 was the recommended oil on some older cars.
I would recommend 10w30 or 10w40 for higher milage engine. IF your under 10 degrees F then run a 0w30.
10w40 is a thicker oil than 5w30. I would only use 10w40 in an older motor in the summer, if the motor was using too much 10w30. The thinner oil will not have the higher pressure. Pressure that this motor needed.? I would go back to the 10w40 and see if the knocking stops...the damage may already be done.
yes, but it's not recommended or good for the engine. 5w30 is the factory recommended oil. it's not as thick, where 10w40 will likely clog the engine.
Yes, they can be mixed.
The W stands for Winter. The 5w30 flows easier at lower temperatures. It is a 5 weight oil at low temperatures where the 10w40 is a 10 weight at low temperatures.
I think you can mix them without doing any damage to the engine. I think you can even add a quart of synthetic oil to regular oil if your engine is low on oil. Generally you would want the 5-30 in an area where it is colder.
10 40w engine oil!
When you see a W on a viscosity rating it means that this oil viscosity has been tested at a Colder temperature. The numbers without the W are all tested at 210Â° F which is considered an approximation of engine operating temperature. In other words, a SAE 30 motor oil is the same viscosity as a 10w-30 or 5W-30 at 210Â°. The difference is when the viscosity is tested at a much colder temperature. For example, a 10W-30 motor oil performs like a SAE 10 motor oil would perform at the cold temperature specified, but still has the SAE 30 viscosity at 210Â° F which is engine operating temperature. This allows the engine to get quick oil flow when it is started cold verses dry running until lubricant either warms up sufficiently or is finally forced through the engine oil system. The advantages of a low W viscosity number is obvious. The quicker the oil flows cold, the less dry running. Less dry running means much less engine wear. A 10w40 oil has a higher weight at 210* than a 10w30 oil. Obviously the use of a 10w40 in a modern engine would be foolish. Modern engines are built to much closer tolerances than engines of a decade ago. 10w40 does not flow as well at 210*, this causing engine wear.
Use 10W40 non synthetic or 75w90 Gl3
9 to 10 quarts depending on which oil filter you use