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Toyota’s New 0W-8 Motor Oil is Too Thin?

Here’s what an engine oil expert has to say about Toyota’s switch to an even thinner motor oil. Plus, did a Toyota Dealership Service Department really follow Toyota’s oil change recommendation or a cheaper alternative?

Yesterday we learned from a licensed oil lubrication specialist that new engines really do need a break-in period using specially formulated break-in oil. In addition, we also learned that engines are not broken in at the factory before being sold to the public; and, why automakers no longer provide car owners with the needed break-in oil.

Today we go a little further into the oil needs of your Toyota with a recent reveal from a licensed lubrication specialist (Lake Speed, Jr.) host of The Motor Oil Greek YouTube channel who has this to say about Toyota’s 0W-8 motor oil recommendation―the thinnest one yet put into Toyota vehicles.

What Does It Mean That My Oil is Thin?

Modern models of Toyota have switched to an overall thinner oil designated by the SAE code as SAE 0W-16. This means the oil is less viscous in both its cooler and warmer temperature designations than say the older 5W-30 or 10W-30 you may have used in your older Toyota. Therefore, SAE 0W-16 is a thinner oil in an overall comparison

What Do the Numbers Mean in Engine Oil?

When it comes to understanding the viscosity of oil and know if you are adding the correct oil to your car, all you have to do is take note of the alpha-numeric code plainly visible on your engine’s oil reservoir cap or the oil recommendation in your car’s owner’ manual. Typically you will see coding such as 10W-30, 20W-40, 5W-30, etc.

This code was created by the Society of Automotive Engineers (SAE) as a viscosity grading system to designate the differences between single-grade (like the “SAE-30” you see on your lawn mower motor oil bottle) and multi-grade (“SAE 10W-30” on your car’s motor oil bottle) motor oils.

The reason for this SAE code has to do with viscosity and changing engine design as engines are continually being redesigned for increasing fuel efficiency. Think of it this way: although motor oil is designed primarily to lubricate moving parts to lessen the rate of wear on your engine, thicker oils put more drag on those moving parts than a thinner oil does. This in turn lowers a vehicle's fuel efficiency.

Can I Use the Same Motor Oil I’ve Always Used?

In short, “NO!” At least not in most cases when we are talking about what you used in an older car for years and what you should be using in a newer car today.

Your newer model engines are physically designed to handle thinner oils. Using a thicker oil can adversely affect your engine. The reasons for this include:

  • Tolerances between moving parts may be narrower or tighter---squeezing a thick oil film into a thinner tolerance can affect the actual lubrication.
  • Oil passages likewise may differ in size to affect the flow and thus internal oil pressures within the engine.
  • The oil pump(s) may be designed to handle a specific viscosity grade.
  • Some models may have internal oil cooling units to further control viscosity within the engine during differing times of operation and conditions.
  • The thinner oil may have different additives (such as those to increase cooling and resist boiling off of the thinner oil) the engine needs to operate that the thicker oil might not possess or need.

Is Toyota’s 0W-8 Oil Too Thin for My Toyota?

When it comes to the trend of newer engine designs, motor oil viscosity is lessening significantly. However, is there a limit to just how thin an oil can be and still impart its lubricating and wear protection properties?

This is a good question. And one that needs answering.

In fact, a recent The Motor Oil Geek YouTube channel episode, the host (a tribologist who specializes in understanding how friction, wear, and lubrication interact with each other in car engines) addressed this question just yesterday in a new video while discussing his daughter’s Made-in-Japan 2023 Corolla that is due for an oil change at just over 10,000 miles by the dealership as part of their free Toyota Care service.

Follow along with the host and learn some interesting facts about Toyota’s thinnest motor oil that includes:

  1. Why you should not worry about the latest recommended motor oil being too thin.
  2. Why we have not seen 0W-8 motor oil on the shelves yet, despite being recommended for the 2023 Toyota Corolla.
  3. What the dealership Toyota Care service actually put into the host’s daughter’s Toyota for its 10,000-mile oil change service.
  4. Why CVT transmissions need fluid changes earlier than recommended by the owners’ manual.
  5. The difference between transmission fluid types.
  6. Why transmission fluid is almost always red in color.

Please Note: In case you do not have the time to view the video, a summary is provided immediately following the video that highlights what was found and what you need to know.

0W-8 Motor Oil: Too Thin to Trust? Let's Find Out!

Toyota Motor Oil Video Summary

  • The previous break-in oil changes using 0W-16 motor oil by the host on his daughter’s car showed a nice decrease in wear rate (as an engine should) with oil samples detecting and measuring specific wear metals captured in the oil that lessened with each sequential oil change.
  • Multiple early oil changes before the recommended 10,000-mile oil change definitely benefit the engine during its break-in period.
  • The dealership garage did use the new (and Toyota-recommended) 0W-8 motor oil in the serviced oil change. This is refreshing news as often there are claims dealership garages do not always use the oil they should.
  • 0W-8 motor oil is very similar to the previously recommended 0W-16 motor oil but does have some additive differences.
  • Toyota’s newest 0W-8 oil is not too thin for today’s Toyota models.
  • The analysis of the CVT fluid proved to be in great shape with a formulation optimal for a CVT type of transmission.

Does Using 0W-16 Instead of 0W-8 Risk Voiding the Manufacturer’s Warranty?

While not exactly following the manufacturer recommendation can increase the risk of your car’s warranty being voided, when it comes to the oil you choose to put in your car the general rule is that you are okay as long as the motor oil being used meets the manufacturer's standards for viscosity, grade, and type as an allowable match for the vehicle.

Related article: Is the Cheaper Costco Kirkland Oil Miserly on the Additives Your Car’s Engine Needs?

For additional articles related to what you need to know about your motor oil and changing your motor oil, here are three recommended popular articles for your consideration:

Timothy Boyer is an automotive reporter based in Cincinnati. Experienced with early car restorations, he regularly restores older vehicles with engine modifications for improved performance. Follow Tim on  “Zen and the Art of DIY Car Repair” website, the Zen Mechanic blog and on Twitter at @TimBoyerWrites  and Facebook for daily news and topics related to new and used cars and trucks.

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Image source: Deposit Photos


Rudy Gyuka (not verified)    April 3, 2024 - 7:16PM

Question for you, would Mobile 1 fully synthetic 0-20W meet the viscosity and lubrication requirements at various-similar temperatures and tolerances as this Toyota specific 0-8W oil?
Enquiring minds.... :-)