In this post guys, we’re addressing a hot topic: Can you use synthetic motor oil in older cars? We’ll also tackle some related questions, including:
- Can synthetic motor oils cause leaks in old cars?
- If your car is consuming a lot of oil, should you switch to a thicker oil?
- When should you consider using high mileage oil?
Can You Use Synthetic Oil in Older Cars?
Let’s cut to the chase: Yes, you can definitely use synthetic motor oil in older cars, whether your vehicle is 30 years old or even a classic vehicle. Synthetic oils have been available for commercial automotive use since the 1970s, and many vintage cars can actually benefit from them.
For classic Porsches for example, with larger engine clearances, known brands such as Mobil 1 or Amsoil, both offers 5W-50 and 15W-50 options. The belief that synthetic oils can’t be used in older cars likely comes from issues with early ester-based synthetics, which could excessively swell engine seals if their concentration was too high.
However, modern synthetic motor oils undergo extensive testing for seal compatibility, so they won’t cause leaks.
Why Some Believe Synthetic Oils Are Bad
A common misconception is that synthetic motor oils, due to their higher cleaning power, might remove sludge and expose leaks.
While it’s true that synthetics have more detergents and dispersants, keeping your engine clean is beneficial. Sludge can block oil passages, which can lead to stalling or engine failure.
If your engine has leaks, they’re often due to failed seals, not the oil itself. Using sludge as a fix for leaks is like putting a Band-Aid on a bigger problem—it’s not a solution.
If Your Car is Consuming Oil, Should You Use Thicker Oil?
For older engines that are burning or consuming a lot of oil, switching to a thicker oil might help, but it should be a last resort.
Always follow the viscosity recommended by your vehicle’s manufacturer. As engines wear out, clearances increase, which can make thinner oil inadequate for maintaining pressure.
Thicker oil might help maintain pressure in these cases, but it won’t fix underlying wear issues. Also, if your engine is leaking oil, a thicker oil won’t solve the problem; the issue is likely a failed seal, not the oil’s viscosity.
If your older engine is burning through oil or showing low oil pressure, might a thicker oil be beneficial? Generally, it’s best to stick with the viscosity recommended by your manufacturer.
However, if your engine has significant wear and is struggling with oil pressure, using a thicker oil might help. Switching to a thicker oil might temporarily extend your engine’s life.
Again, this should be considered a last resort rather than a preventive measure. While higher viscosity oils can help maintain oil pressure and reduce burn-off, they won’t solve the underlying issues of engine wear.
When to Use High Mileage Oil
High mileage oils are formulated for engines with significant wear and can help manage oil burning and leaks.
They include seal-swelling agents that recondition aging seals to reduce leaks. While high mileage oil can extend the life of older seals and decrease oil consumption, it is not a substitute for replacing a majorly failed seal, which remains the ultimate solution.
Bonus Fact: Synthetic Oil in Rotary Engines
You might have heard that rotary engines can’t use synthetic motor oil because it could lead to carbon deposits.
This myth probably stems from early experiences with synthetic motor oils. Rotary engines inject oil directly into the combustion chamber, where it burns off regardless of whether it’s synthetic or conventional. In motorsport, synthetic oils are commonly used in rotary engines, often mixed with fuel to tackle oil metering issues.
Conclusion
To sum up: Yes, synthetic oils are safe for old engines, can help manage oil consumption, and using a thicker oil may be beneficial if your engine is showing signs of wear.
Do you have questions or feedback? Drop your comments in the box below.
