5 Common Oil Service Questions Answered

Oil lubricates parts; serves as a coolant; and helps circulate dirt and other particles out of the engine and through the filter, where they can't do any harm.

Oi change service questions answered

It also protects the surfaces of engine parts from rust and corrosion when the engine sits for long periods of time. It's pretty basic, but also incredibly essentially to your motor's health. Here are five things every mechanic should know about motor oil.


Buy engine oil

Buy oil filters


1. What Do Motor Oil Numbers Mean? 

Many people believe the "W" in the number for motor oils stands for "weight," but it actually stands for "winter." These numbers are derived from a test where the oil is heated to a certain temperature and then timed as it drains out of a hole with a specific diameter. So the lower the time, lower the number. It also indicates a lower viscosity, which basically means the oil is thinner.

Oil change service questions numbers

Your engine oil has to be thin enough when it's cold to circulate during cold starts and thick enough to protect the engine when it's running and hot. As temperature rises, viscosity falls. The oil then gets thinner and it flows easier. The first and second number in an oil type like a 10W-40 represents a balance between being thin enough to be effective when you start the motor in winter, but thick enough to stick to and protect components in summer heat.

2. Is it Time to Change the Oil When it's Dark?

Maybe, maybe not. Your oil is the custodian of your engine. It picks up the trash and moves it to the oil filter, which is like the dumpster. As soon as you change your oil, your new batch is going to start changing colors as it picks up particles and circulates them toward the filter. 

old motor oil

If your oil is starting to look darker, it's just doing its job. Think of it this way: when you change your oil, it's going to be darker than when you put it in, but a darker color doesn't necessarily mean it's time to change it. Ultimately, you should just follow the maintenance schedule provided by the manufacturer for your machine.

3. Do I Have to Change the Oil Filter With the Oil?

As a rule of thumb, yes. The filter is the dumpster for all of that trash that is floating around in the engine. So when there's no more room in that dumpster, the trash does a U-turn back into the engine. Changing the filter ensures that there's room to capture those contaminants your oil shuttles away from your engine components. 

Motorcycle oil filter change

4. Should I Switch to a Synthetic Oil?

The technology used to create today's synthetic oils is highly sophisticated. Today's synthetics are essentially designer oils, formulated with properties perfectly tailored to their application. There are basically two types of synthetic oils: 

  • Class III: Synthetics that are actually mineral oils based on petroleum stocks
  • Class IV: Synthetics that are built from the bottom up in the lab 

Synthetics can outperform their petroleum oil counterparts due to their more refined formulas, which better protect your engine from wear by keeping it cleaner than petroleum. 

synthetic oil change

Like any product that's a little different, synthetic oil comes with skepticism. Some seal compatibility issues occurred with synthetic oils years ago. In other words, they had a tendency to leak, but not anymore. Synthetics also didn't allow engines to break in properly, but this was an issue of the past. Motorcycles often come filled with synthetics straight from the factory these days. You shouldn't shun synthetics altogether, but if the manufacturer of your machine recommends using conventional oil, you should stick with that. 

5. Can Motor Oil Expire?

It sure can, so once the expiration date is in the rearview mirror, expect the oil to not perform as well if you continue using it in your machine. Motor oil is more than just oil. It contains a lot of other chemicals, and those chemicals can break down and undercut the oil's performance. Always check to see when the oil expires and make sure you change it when it's past its shelf life.

Need to change the motor oil on your motorcycle? Watch the video above to learn how to change the oil in a Honda motorcycle.


Why Partzilla?

Commercial Discounts

Special discounts for companies in the powersports industry


Government Sales

Discounts for federal and most state and municipal agencies