Is 0w-20 Motor Oil Too Thin?

A reader asks: The engine oil recommendation for my new pickup truck is 0W-20. I’ve never owned a vehicle that used anything other than 5W-30, so this is a big change. A 0W-20 oil seems too thin and I’m very skeptical. I asked my dealer if I could at least use 5W-20 and they insist that 0W-20 must be used to maintain my warranty. Is 0W-20 safe for my new engine?

Our answer: Yes, 0W-20 is unquestionably safe for your engine. Manufacturers have been specifying 5W-20 and 0W-20 since the early 2000’s. There is absolutely no evidence that engine wear rates have increased because of 20-weight engine oils. Engine designs and materials along with motor oil chemistry have made massive strides in the last 15 years. Therefore, engine wear has never been lower. The 5W-30 grade has been rapidly supplanted by 5W-20 and 0W-20 for new cars. New vehicles specifying 5W-30 is now a rarity. In fact, even lower viscosities like 0W-16 are now creeping into the industry.

Why are car makers suggesting thinner motor oils? Quite simply to optimize fuel economy. But this trend has gone on for long enough for us to conclude that there is no downside in terms of shorter engine life.

As for the second part of your question about substituting 5W-20 for the recommended 0W-20, we see absolutely no advantage to doing this. Let’s use the specifications of the AMSOIL Signature Series 0W-20 and 5W-20 to illustrate our point.

The industry standard for evaluating viscosity at operating temperature is the measured in “centistokes” at 100°C.

• AMSOIL Signature Series 0W-20: 8.8 centistokes
• AMSOIL Signature Series 5W-20: 8.7 centistokes

Therefore, at operating temperatures, 0W-20 and 5W-20 are virtually identical in terms of actual viscosity. The reason that the vehicle manufacturer opted for a 0W-20 oil is because it would offer a very slight improvement in terms of cold weather start-up protection.

Our daily driver calls for a 5W-20, but we opt for a 0W-20 for year-round use, just so that we have the best possible start-up protection. We see absolutely zero oil consumption between oil changes, even in scorching temperatures.

So the the bottom line is that you can rest assured that a quality 0W-20 motor oil will offer the utmost wear control. Enjoy your new truck and rest assured that it will be fine using 0W-20 motor oil.