Should a 100,000 km old car use 30 or 40 oil?

[CollinAnn]

For an old car with 100,000 kilometers, the wear and tear on components such as the valve train and crankshaft connecting rod mechanism are already quite severe. Therefore, it is advisable to choose 40 oil, which has a higher viscosity. Engine oil, motor oil, or engine lubricant is a substance enhanced with additives in base oil, primarily containing anti-wear additives, detergents, dispersants, and multi-grade viscosity index improvers. Flow differences: 30 oil has better flowability than 40 oil, which can further reduce fuel consumption and dissipate heat from the engine more quickly. Engine noise differences: For older cars, using 30 oil may result in slightly louder engine noise compared to 40 oil. Oil consumption differences: For engines that strictly require 40 oil, using 30 oil may lead to higher-than-normal oil consumption (commonly known as burning oil). Stability differences: 40 oil offers better oil stability than 30 oil under extremely high-temperature conditions in the engine. Engines that strictly require 40 oil may experience higher-than-normal oil consumption.

[Duncan]

I've been driving for over ten years, and my old car has clocked over a hundred thousand kilometers. Choosing between 30 or 40 viscosity oil depends on the car's condition and driving habits. Generally, engines with over a hundred thousand kilometers have some wear and slightly larger gaps. Using 40 viscosity oil, which is thicker, can better fill those small gaps and provide better protection. If you drive aggressively or frequently take long trips, 40 is more suitable as it reduces oil consumption and engine noise. For stop-and-go city driving with less engine wear, 30 can also be used, performing stably in high summer temperatures. Also, don’t just focus on viscosity; make sure it’s synthetic or semi-synthetic oil with an API standard of SN or higher. I recommend trying 40 once, and if there are no issues, stick with it, just check the oil level regularly.

[McCecilia]

As a long-time owner who maintains classic cars, my experience is that for vehicles over 100,000 kilometers, 40-weight oil should be prioritized. I've driven several high-mileage cars myself, and after trying different oils, I found that 40 viscosity offers more advantages for aged engines. Over time, internal engine components may experience slight wear, and the thicker consistency of 40-weight oil forms a more substantial oil film, reducing friction and noise. If you live in a hot climate or during summer high temperatures, 40-weight oil is less prone to thinning and oil burning. Don't hesitate to check the manual recommendations—many manufacturers also provide viscosity charts for reference. By the way, regular oil changes are crucial; for older cars, change every 5,000 kilometers to prevent issues from worsening and affecting performance.

[StKylie]

As someone who just graduated from being a novice, I also struggled with oil choices when I first drove an old car with 100,000 kilometers. Simply put, if the car is old but well-maintained, 30-weight oil is sufficient and more cost-effective. However, if the engine has abnormal noises or burns oil, switching to 40-weight is better—the higher viscosity provides better protection for engine components. Don’t blindly trust online opinions; first check the oil level to see the actual effect or consult a mechanic. When maintaining an old car, don’t skimp on small expenses—spending thousands later on engine repairs would be a bigger loss.

[MacTessa]

As car enthusiasts love to discuss details, choosing between 30 or 40 viscosity oil for older vehicles requires considering multiple factors. The viscosity numbers represent flow characteristics - 30 being thinner and 40 thicker, which suits worn engines especially after high mileage when stronger oil film is needed to prevent increased fuel consumption from excessive clearances. Considering driving conditions, opt for 40 for mostly highway driving while 30 works for city commuting, and always choose synthetic oil for enhanced durability. Incidentally, while oil choice slightly affects fuel economy, making the right selection primarily ensures engine longevity - don't forget regular filter changes too.

[SanSebastian]

After driving an old car for many years, I often remind my friends to prioritize using 40-grade oil for vehicles over 100,000 kilometers—safety first. Engine clearances may increase, and thicker oil can provide better lubrication to prevent abnormal noises or oil burning. In severe cases, power loss may occur. When temperature fluctuations are significant, viscosity changes can affect startup. Check maintenance records and select the matching oil grade. Avoid saving money by using inferior oil, and regularly consult technicians during maintenance to reduce risks.