Can fully synthetic oils from different brands be mixed?
4 Answers
Fully synthetic oils from different brands should not be mixed. Although the base oils are similar, the processing techniques and additives vary between brands, and even different grades within the same brand may use different additives. Mixing them can lead to chemical reactions between the additives, causing the oil or hydraulic fluid to lose its original physical and chemical properties. This can result in the failure of lubrication, cooling, and pressure transmission functions, potentially leading to vehicle or mechanical failures or even severe damage. Fully synthetic oil is a product of modern chemical technology advancements, offering superior lubricity, lower friction resistance, resistance to oxidation, and strong cleaning properties compared to mineral oil.
I think it's best not to mix different brands of full synthetic engine oils, mainly because their formulations vary too much. The base oils of full synthetics are similar, but the additives each brand uses—like detergents, anti-wear agents—are completely different. Mixing them could trigger chemical reactions that form sediment or clumps, compromising lubrication. If oil passages get clogged or oil pressure drops, the engine risks overheating or accelerated wear. From cases I've studied, some owners had no immediate issues with temporary mixing, but long-term it hikes maintenance costs. In emergencies like running low mid-trip, a small amount of the same grade full synthetic can be mixed as a stopgap, but switch back to a single brand ASAP. Using matched oil during maintenance with regular changes saves money and protects your engine.
As a seasoned DIY car enthusiast, I once experimented with mixing different brands of full synthetic oils, only to find the oil turning cloudy – likely due to additive incompatibility. The short-term lubrication suffered, with faint abnormal noises during acceleration. Fortunately, I changed it promptly to avoid major issues. Now I strictly stick to a single brand to avoid formulation compatibility headaches. While mixing might save a few bucks, potential engine damage could cost far more in repairs. Always consult your manual's recommendations before oil changes – that's true wisdom.
I personally believe that mixing different brands of fully synthetic oils is absolutely unacceptable due to significant risks. Each brand's additive system is independently designed, and mixing them may lead to failure or adverse reactions, resulting in sludge buildup or lubrication film breakdown. Vehicle manuals typically emphasize using consistent oil products, and it's best to adhere to this advice. If accidental mixing occurs, it's essential to perform a complete oil change with fresh oil as soon as possible to prioritize engine health and safety.
