"Is synthetic really worth it?" is the question I hear more than any other. The honest answer is that it depends on how you drive and what you drive. But it helps to know what's actually different about the oil first.
Where the difference starts
Conventional motor oil starts as crude oil that's refined down to a lubricating base. Refining removes a lot, but the result is still a mix of molecules in all different shapes and sizes, along with some impurities that were never fully removed.
Synthetic base oils are built to be far more uniform. When the molecules are more alike, the oil behaves more predictably. It doesn't thin out as much when it's hot or thicken up as much when it's cold, and it holds up longer before it starts to break down.
Both kinds of oil then get an additive package: detergents, anti-wear agents, anti-foam agents and so on. The base oil is what those additives ride on, so a stronger base gives them a better start.
Where synthetic earns its keep
- Heat. Towing, hauling, turbocharged engines and stop-and-go traffic all run oil hot. Heat is what breaks oil down, and synthetics resist it better.
- Cold starts. On a January morning in Schaumburg, oil that flows quickly reaches the top of the engine sooner. More on that in an upcoming post.
- Longer drain intervals. Because it breaks down more slowly, a quality synthetic can safely go longer between changes. AMSOIL publishes recommended intervals for each of its oils in its drain interval guide. If your vehicle is still under warranty, follow the interval in your owner's manual.
- Engines that call for it. Many newer cars require a synthetic or synthetic-blend oil to meet the manufacturer's specification. Your owner's manual will say so.
Where it matters less
If you drive an older car gently, mostly highway miles in mild weather, and change your oil on schedule, a good conventional oil will do the job. Synthetic still gives you extra margin, but the difference is smaller.
Two myths worth clearing up
"Switching to synthetic causes leaks." It doesn't. Modern synthetics are compatible with engine seals. If an older engine starts seeping after a switch, the seal was usually already worn and the old sludge was plugging the gap.
"Once you go synthetic, you can't go back." You can switch back and forth, and you can even mix brands in a pinch. Just stay with the viscosity and specification your manual calls for.
What matters most
Whatever you choose, use the viscosity (like 0W-20 or 5W-30) and the specification your owner's manual lists, and change it on time. AMSOIL has a good side-by-side explainer on synthetic vs. conventional oil. When you're ready, the vehicle lookup shows exactly which AMSOIL oil and filter fit your vehicle.
AMSOIL introduced its first synthetic motor oil back in 1972, and the products have come a long way since. If you're not sure whether synthetic makes sense for your driving, send me a note and I'll give you a straight answer.
Questions about your vehicle or equipment?
Send Byron the year, make and model and he'll point you to the right products.