Mixing Motor Oil According to Mobil Oil, it should be fine to mix oils. So, if you are low on oil, don't be afraid to add a quart or two of synthetic oil if you are using regular oil or even regular oil if you are using a synthetic..
Just so, can you mix 5w30 and 10w30?
Keep in mind oils do not mix if you have 5w30 and add 10w30 it won't give you a blens both oils will stay seperate so you will have a few quarts 5w30 and a quart 10w30 they never mix.
Similarly, can you mix 5w20 and 10w30? You can mix 10W & 30W to get 20W or you can mix 5W20 & 10W40, but you do not want to mix 10w & 10W30. In other words, it's OK to mix straight weights or multigrades but not straight weights & multigrades.
In this way, can you mix different oil weights?
Answer: Mixing two different motor oil weights to make your own custom viscosity does not work quite as simply as it sounds. There a couple of unknowns and even some potential complications that have to be considered. If you are insistent on SAE 40 oil, consider AMSOIL Synthetic Premium Protection 10W-40 Motor Oil.
Can you mix 5w30 and 5w20 oil?
Yes, you can. It is best if they are from the same brand and level of API service to be the same formulas, but they are certainly compatible, even if different formulas and brands. I once needed oil on a trip, and my car had 5W-20n ILSAC approved oil in it as recommended by the factory.
Related Question Answers
Will it hurt to put 10w30 in a 5w30 engine?
yes 10w30 should meet the same standards as 5w30 just will not go as low temp.What happens when you mix oil viscosities?
Different oil viscosities will not separate or react negatively to each other because the base oil is molecularly the same. It's the different oil additive systems between brands that shouldn't be mixed - if you're concerned about the oil performing exactly how it was designed.Is it OK to mix engine oils?
Mixing Motor Oil According to Mobil Oil, it should be fine to mix oils. Many oils are a blend of natural and synthetic oils. So, if you are low on oil, don't be afraid to add a quart or two of synthetic oil if you are using regular oil or even regular oil if you are using a synthetic.Is it bad to mix oil in your car?
The good news is that mixing different types of oil it will not harm your engine in any way in the short run. Most synthetic and semi-synthetic engine oils are based on regular oil and are compatible. Now, as far as different grades are concerned, mixing between them isn't something that will damage your engine either.Which is better 5w30 or 10w30?
A higher viscosity oil, such as 10w30, will flow slower at low temperatures compared to a lower viscosity oil like 5w30. A higher viscosity or thicker oil will seal better than a low viscosity oil. A thicker oil will also provide better lubrication of critical engine parts.Can you mix synthetic oil with regular oil?
The simple answer: Yes. There is no danger mixing synthetic and conventional motor oil; however, conventional oil will detract from the superior performance of synthetic oil and reduce its benefits. So, yes, you can safely mix synthetic and conventional oil.Is it okay to go from synthetic oil to regular oil?
Answer. Synthetic oils typically provide better protection than conventional oils, but switching back and forth between full synthetic and conventional oil will not damage the engine.What happens if you use the wrong weight oil?
The brand of motor oil matters little, but its viscosity grade (10W-30, for example) is important. Use only what the owner's manual specifies. Using the wrong oil can lead to reduced lubrication and shorter engine life. If the manual says to use synthetic oil, do so.What happens if you use 5w 20 instead of 5w 30?
Due to the increased resistance of the thicker 5W-30 oil, your engine will produce slightly lower fuel economy and horsepower output. You also risk engine damage when using 5W-30 instead of 5W-20, as the internal engine components are specifically designed to be used with 5W-20 motor oil.What does 5w30 mean?
In a 5W-30 for example, the number before the W describes the viscosity of the oil at low temperatures. The lower the number, the thinner the oil and the better the oil's cold temperature/ cold start performance. The number after the W describes how thick the oil is at the engine's normal operating temperature.Can I mix 10w30 with 10w40?
You will be fine with that. They will mix right in with each other and no harm will be done. Even if you were to mix syn with conventional you'll be fine. If you were to labratory test your oil it will read out as not a true 10w-30 but no harm will be done.Can I use 10w 40 instead of 5w40?
10w40 is thicker than 5w40, ONLY when cold. At operating temperature it is exactly the same. Multi-viscosity oils with a lower W number are specifically designed to flow better, and thus lubricate better, at very low temperatures. There is no need to use a 5w-40 if the vehicle only requires 10w-40.What is a 30 weight oil?
The "W" in 10W-30 oil stands for "weight." Oil changes its viscosity with temperature and the single viscosity rating only represents the flow of oil when it's warm. Thus, SAE 30 oil takes approximately 30 seconds to flow through the tube. This single viscosity rating is sometimes called the oil's "weight."Can you mix oil viscosities?
Chris says, “Yes it is possible to alter engine oil viscosity by mixing two different viscosity grade engine oils. Also, with respect to the winter grade, mixing oils with disparate winter grades will result in some undefined combination winter grade.Will 5w20 hurt a 5w30 engine?
Swapping 5w20 for 5w30 would *not* be a good idea. If the manufacturer of your car doesn't spec 5W20 oil then you shouldn't use it. The oil will be too thin (the smaller the number the "thinner" the oil) to provide the needed protection for your engine.What happens if you use 10w40 instead of 5w30?
5W30 means that the oil has a thinner consistency in cold weather and will protect your engine at lower temperatures, at less thickness than 10W30. 10W30 means the oil will be a little thicker at the same lower temperatures, and will then protect the engine the same as 5W30 at higher (operating warm) temperatures.What happens if I put 10w30 instead of 5w30?
What will happen if I used 10w30 on a car that takes 5w30? 5W means that is the category of oil when it is cold(starting temperature). replacing it with a 10W-xx only changes the very cold thickness, such that it is only half as thick as molassas when at -40. then you have a problem, the oil will get too thick to flow.Does brand of engine oil matter?
No. Switching brands is not harmful to your engine as long as you choose an oil marked with the API donut of the same level, e.g., API SN. You may give up enhanced performance if you switch from synthetic or high mileage to conventional oil. MYTH: When motor oil becomes dark, that means it's time to change it.Can I put thicker oil in my car?
A: Yes. This is a practical method to improve oil pressure in an older, high-mileage engine. The slightly thicker oil film from the heavier base weight oil — 10W — can help protect worn engine bearings as well. 
