Is Valve Noise Caused by Thin or Thick Engine Oil?

[VonCassidy]

Both excessively thick or thin engine oil viscosity can cause valve noise. If the oil viscosity is too thick, it can affect the normal operation of the hydraulic system, leading to insufficient oil supply and resulting in valve noise. If the viscosity is too thin, it cannot provide adequate lubrication, which over time can cause severe engine wear. Combined with reduced oil pressure, this also leads to valve noise. In terms of engine structure, valves are divided into intake valves and exhaust valves. The intake valve's function is to draw air into the engine to mix with fuel for combustion, while the exhaust valve's role is to expel the burned exhaust gases and dissipate heat.

[EmeryRose]

This is a common issue I encounter during car repairs. Valve noise is primarily related to valve clearance, and oil viscosity does have an impact. If the oil is too thin, the oil pressure won't build up sufficiently, leading to inadequate oil supply to the hydraulic lifters, which can cause a ticking sound. However, oil that's too thick has poor fluidity, and inadequate lubrication during cold starts can also result in abnormal noises. My old Jetta suffered from this before - using overly thin oil in summer made the valve noise sound like a clapper. I recommend sticking to the oil grade recommended by the manufacturer and not arbitrarily changing the viscosity. Also, don't forget to check for wear on the valve lifters - this is the root cause of the problem. Older cars especially need regular valve clearance adjustments.

[Daniela]

I've been running a repair shop for over a decade and handled numerous cases of valve noise. Thin engine oil does make valves more prone to knocking, especially in cars that are seven or eight years old. When the oil is thin, the oil film strength isn't sufficient at high temperatures, and the hydraulic lifters don't get enough oil pressure, resulting in that tapping sound. However, using high-viscosity oil in winter isn't the solution either—when the engine is cold, the oil pump can't circulate the thick oil properly, and the lifters won't get lubricated, causing the same noise. Just last week, a customer used 0W20 oil, and the valve noise ended up louder than the engine itself. The key is to use the right viscosity—stick with what's recommended in the maintenance manual, like 5W30, for the safest bet. And remember to change the oil regularly; sludge buildup will render any viscosity useless.

[Greyson]

As a graduate in automotive repair, this issue needs to be analyzed case by case. Using thin oil in new cars is generally not a problem, but for older engines with larger oil passage clearances, thin oil can easily lead to insufficient oil pressure, causing the valve lifters to make a clicking noise. Conversely, oil with excessively high viscosity flows slowly at low temperatures, resulting in inadequate lubrication during cold starts, which can also cause abnormal noises. Last time when dealing with a customer's valve noise issue, I first measured the oil pressure and then switched to a full synthetic oil with standard viscosity, which significantly reduced the noise. However, valve noise can also stem from rocker arm wear or excessive clearance, so don't just focus on the oil. For regular maintenance, always use genuine oil filters, as inferior filters can also affect oil pressure.

[LeHarmony]

Having driven over a dozen cars, my experience tells me that valve noise is indeed related to oil viscosity. When I drove a domestic car in the past, I used thin oil to save money, and the valves rattled like frying beans. The mechanic said that thin oil has a weak oil film, and older cars have poor sealing, so the oil pressure can't support the hydraulic lifters. However, oil that's too thick is especially noticeable in winter—during the first few minutes of startup in sub-zero temperatures, the noise is particularly loud. Now, I strictly follow the manual's specifications when changing oil, and 5W30 works best year-round for peace of mind. By the way, a reminder: increased valve clearance will make the noise more obvious, so it's best to check the valve mechanism at 60,000 kilometers and adjust it if necessary.

[DeLouis]

This issue needs to be analyzed based on the engine type. For older mechanical lifter engines, thicker oil provides better cushioning effect and reduces noise. But nowadays most engines use hydraulic lifters, where thinner oil is actually more suitable as its better flow allows quicker oil pressure buildup. I encountered a case where valve noise increased after switching to high-viscosity oil precisely because excessive thickness caused lifter response lag. In fact, the OEM-recommended viscosity has undergone millions of tests - don't modify it arbitrarily. If valve noise occurs, first check for overfilling or degraded oil, both affect pressure. Prevention beats cure - stick to scheduled oil changes.