Why Oil Viscosity Matters: 0w20, 5w20, 5w30 Explained

Why Oil Viscosity Matters: 0W-20, 5W-20, and 5W-30 Explained

Looking for the best auto repair shop in St. Louis? Sant Automotive helps drivers in Webster Groves, Affton, Crestwood, and South St. Louis County protect their engines with the right oil and the right maintenance schedule.

One of the biggest changes in modern vehicle maintenance has been the type of engine oil manufacturers recommend.

Years ago, heavier oils like 10W-40 were common. Later, 10W-30 and 5W-30 became popular. Today, many vehicles require lighter oils such as 5W-20 or even 0W-20.

Why Do Newer Vehicles Use Lighter Oil?

Modern engines are built with tighter tolerances and greater precision than older engines.

That means manufacturers often recommend lighter oils because they help with:

• Faster lubrication at startup
• Reduced internal friction
• Improved fuel efficiency
• Better flow through tight engine passages

In other words, if the engineers who designed the engine specified a certain oil, it is usually best to follow that recommendation.

What Happens If the Wrong Oil Is Used?

Using the wrong viscosity can lead to:

• Poor lubrication during startup
• Reduced fuel economy
• Increased engine wear
• Improper oil flow in critical engine areas

That is why oil type matters just as much as oil change interval.

Why Sant Automotive Recommends 5,000-Mile Oil Changes

At Sant Automotive, we recommend 5,000-mile oil change intervals for most vehicles.

That recommendation is based in part on the oil consumption issues many modern vehicles are experiencing.

The goal is simple:

Protect the engine, maintain proper oil level, and help prevent expensive repairs.

We Use Mobil Super™ Synthetic Oil

Sant Automotive features Mobil Super™ Synthetic motor oil for oil change service.

This helps provide:

• Strong wear protection
• Improved resistance to heat and breakdown
• Reliable performance in real-world driving conditions

Combined with a 5,000-mile service interval, it is a smart way to protect your engine over the long term.

Oil Changes Are About More Than Oil

A good oil change visit is also a chance to monitor your vehicle’s overall condition.

Routine service can help catch:

• Leaks
• Fluid issues
• Brake wear
• Tire problems

For more on staying ahead of maintenance, see our guide on how much a car check up costs in St. Louis.

Schedule an Oil Change in St. Louis

If you are not sure what oil your vehicle needs, or if you are due for service, Sant Automotive is ready to help.

Book Online + Find Us

Sant Automotive • 8720 Watson Rd, St. Louis, MO 63119 • (314) 849-2900

Schedule Auto Repair in St. Louis

Book your appointment online in seconds.

Schedule an Appointment

Prefer phone? Call (314) 849-2900.

Sant Automotive has been recognized as one of the best auto repair shops in St. Louis, earning the ASE Blue Seal of Excellence in 2002 and being named a CarFax Top Shop for two consecutive years.

Free Code Scan vs Real Diagnostics

Free Code Scan vs. Real Diagnostics: What St. Louis Drivers Need to Know

Looking for the best auto repair shop in St. Louis? Sant Automotive helps drivers in Webster Groves, Affton, Crestwood, and South St. Louis County diagnose check engine light problems correctly the first time.

For years, many drivers believed that if their check engine light came on, a quick scan at a parts store would tell them exactly what was wrong.

Unfortunately, that is not how diagnostics works.

What a Free Code Scan Actually Does

A code scan reads trouble codes stored in your vehicle’s computer.

That can be useful—but it only tells you what system reported a problem, not what actually caused it.

For example, a lean condition code may point to:

• A vacuum leak
• A fuel delivery issue
• A sensor problem
• An intake gasket leak

The code is the beginning of the investigation—not the answer.

Why Real Diagnostics Save Money

Replacing parts based on a code alone is one of the fastest ways to waste money.

Modern components like sensors, ignition parts, fuel system parts, and electronic modules are expensive. Once installed, those parts usually cannot be returned.

Professional diagnostics helps you avoid:

• Guessing
• Unnecessary parts replacement
• Repeated repairs that do not solve the problem

What Proper Diagnostics Involves

At Sant Automotive, diagnostics means finding the root cause of the problem.

That may involve:

• Reading fault codes
• Reviewing live data
• Testing system operation
• Checking technical service bulletins
• Using professional-grade scan tools and factory information

That is very different from simply plugging in a generic scanner and reading a number off a screen.

When You Need Diagnostics

Professional diagnostics is the right step when:

• Your check engine light is on
• Your vehicle is running poorly
• Your vehicle failed an emissions test
• You have an intermittent drivability problem

If your vehicle failed emissions, you may also want to review our guide on Missouri readiness monitors and emissions testing.

Why Drivers in St. Louis Choose Sant Automotive

Drivers in Webster Groves, Affton, Crestwood, and South St. Louis County choose Sant Automotive because we believe in diagnosing problems correctly instead of throwing parts at them.

For a full explanation of how we approach problem solving, see our guide on what automotive diagnostics really means.

Schedule Check Engine Light Diagnostics in St. Louis

If your check engine light is on, let Sant Automotive diagnose it correctly the first time.

Book Online + Find Us

Sant Automotive • 8720 Watson Rd, St. Louis, MO 63119 • (314) 849-2900

Schedule Auto Repair in St. Louis

Book your appointment online in seconds.

Schedule an Appointment

Prefer phone? Call (314) 849-2900.

Sant Automotive has been recognized as one of the best auto repair shops in St. Louis, earning the ASE Blue Seal of Excellence in 2002 and being named a CarFax Top Shop for two consecutive years.