It is safe to mix different motor oils for your car engine. But, not all oils are compatible and safe to mix. Can you mix 5w30 and 10w40 oil?
Yes you can mix them! Apparently, these oils are entirely different and deliver different performances at high and temperatures. Mixing the two of them can be safe if they’re from the same brand.
However, there are pretty many things you need to know about mixing motor oils of different viscosities, even when they are from the same brand.
Interestingly, this article details all you should know about mixing 5w30 and 10w40 oils, irrespective of the brand.
Is It Safe To Mix Motor Oils?
When you mix two different oils, you’ve reduced the effectiveness of the additives in both oils as the molecules in each oil would try to adapt to the other.
It is not advisable to mix engine oils regardless of the viscosity, brand, and type. Such an action only reduces the benefits each of the mixed oil is expected to deliver to your car engine.
Apparently, mixing oils shortens oil change intervals. So, while it’s okay to mix motor oils, it is not advisable, and it could bridge the warranty on new cars.
Can You Mix 5w30 and 10w40 Oil?
With what we’ve explained above, the simple answer is YES, you can mix 5w30 and 10w40 oil without bothering of any catastrophic engine damage.
However, since 5w30 and 10w40 have different viscosity and weight, it is advisable to mix them in equal quantities; that is to say, 50% of 5w30 to 50% of 10w40.
It is much better if the two oils are manufactured by the same brand; that way, they would mix much better. Also, it is important to drain out the old oil entirely before pouring the mixed one.
Furthermore, it is important to note that mixing 5w30 and 10w40 might cause oil clumps because they are of different weights.
What Happens When You Mix 5w30 10w40?
10w40 has more weight more than 5w30, and thus, mixing the two could put your engine into much stress. Another possible scenario that could result from mixing these oils is a drop in your car’s fuel efficiency.
However, asides possibly reducing fuel economy and shortening oil change intervals, there’s no other effect of mixing 10W40 and 5w30.
But, nevertheless, on most modern cars, the manufacturers may recommend a particular type/brand of oil to use for the engine.
Going against such recommendations will void the warranty on your car, and may also cause your engine not to deliver its peak performance.
The truth remains that mixing motor oils would not cause your engine to explode, neither would it cause a catastrophic damage to any of the engine components.
However, over time, as you continue using mixed oils, the oil seals may be affected, and the mixed oil could cause sludges inside your engine. These can lead to a damage if not attended to properly.