Imagine this: You need to top up your car’s engine oil (Malaysians call it “minyak hitam”) and instead of buying a full new bottle, you found some lying around the house or inside the car boot. But, it’s not the same type/grade/viscosity nor does it come from the same brand. Your cheapskate frugal self thought it's a good idea to just make use of the lubricant in hand.
Or is it?
So, what will happen if you do mix engine oils from different brands; or mix engine oils with different viscosities/grades? Is it a good idea after all? Why are we saying it will “unalive the engine”? Is it because we can’t say “kill the engine” out loud since your car can actually hear you and then misbehave fr, or are we just trying to be TikTok cool with all this Gen Z slangs?
First of all, before you ask another cheapskate question: half-opened bottles of fresh engine oil – usually the leftovers from previous car services – are best used within one year after opening. If you intend to use this half-empty (or half-full?) bottle of engine oil to topup, you can – considering the bottle cap and lid are sealed nice and tight, kept away somewhere dry and dark… like your bedside drawer or that shelf where you keep those long, unused spoilers.
Secondly, look for the grade or viscosity label. Whether it’s a fresh bottle of engine oil or a leftover one, the viscosity plays an important role. Viscosity simply means how well the engine oil will flow in specific temperatures. If you're unsure of which oil grade viscosity to use, flick through the owner's manual to find the answer for the car you’re driving.
Assuming both are from the same brand; but one is a full-synthetic 5W-30, and the other a semi-synthetic 10W-40. Will mixing these two oils fry your engine? The short answer is no.
During emergencies, it’s OK to mix engine oils with different viscosities if your engine is running low on oil. Any oil in the engine is better than no oil at all. But please remember to change out this ‘rojak concoction’ the first chance you get.
Yes, your engine won’t go totally kaput when it is lubricated with engine oils of different grades. However, don’t expect the performance and efficiency to reach its intended level. Using the recommended oil grade as per the car’s owner manual will ensure the engine runs optimally.
How about mixing engine oils of the same grade/viscosity but from different brands? Yeah, sure, why not. During emergencies, this should make you less anxious compared to the previous scenario.
The thing with different brands of engine oils is their own proprietary blend of additives. Mixing different brands of engine oils won't necessarily cause any harm to your engine. At most, you're just not getting the best engine performance from mixing them because the additives in each brand of engine oil are optimised to be used on their own.
Conclusion
This burning question should only apply to cases of emergency when the car’s engine is running low on oil and in need of a topup. Should that ever happen to you, and someone comes along offering help by handing you a bottle of engine oil, just take it. Drive the car normally and schedule for an oil change as soon as you can.
An almost-OCD car owner, on the other hand, would always come prepared with a fresh bottle of 1L engine oil in the car boot; ready to be used either during emergencies or for the next scheduled service appointment. Conversely, for those who prefer to live life on the edge, feel free to save this article in your collection of “Driving for Dummies” notes.
Keyword: So you heard mixing 2 different engine oils will ‘unalive’ your car's engine? Here’s your answer