The line in Hollywood is that you can't be too thin or too rich. When it comes to high-performance engines, it's better to be a little rich than too lean, but with engine oil, thinner is definitely better. The OEMs are constantly pushing the envelope when it comes to all things that affect efficiency. One of the latest trends is to use thinner viscosity oils in search of more power and better fuel mileage as long as the oil doesn't hurt durability.
Car crafters are always looking for that next performance advantage, especially if it doesn't cost much and all you have to do is open a bottle and pour it in. We decided to take a closer look at thinner viscosity oils and do some testing to see if we could find a little horsepower from a pour spout.
We tend to take oil for granted, but as engine output continues to climb, the oil's job will get more difficult. We tested this Quaker State 5W20 against a more viscous 20W50 and saw a minor improvement in power.
To begin with, we spoke to Quaker State engineer Mark Farner about what goes into this new generation of synthetic engine oils and what kind of advantages they promise. Synthetic engine oil has always enjoyed a reputation both for its high-pressure lubrication performance and also its ability to withstand much higher engine oil temperatures than conventional petroleum-based oil. Conventional oils will tolerate engine oil sump temperatures of up to 250 to as much as 275 degrees F without difficulty. According to Farner, oils like Quaker State's full synthetics can easily withstand sump temperatures in excess of 300 degrees F, and he says that some oval track race teams are experimenting with temperatures as high as 350 degrees F.
For a typical wet-sump engine, 300 degrees F is still extremely hot, but Farner says that synthetics, because of their molecular makeup, are better suited to withstand these temperatures. The downside is that additive packages do tend to break down faster in high-temperature environments, so if you plan on running oil temperatures in excess of 300 degrees, this would mean changing the oil after every track event regardless of the mileage.
For street engines that do not suffer this kind of track-day abuse, merely pouring in a synthetic does not mean that you can radically extend service drain intervals. Petroleum-based oils do not lose their base lubrication characteristics, what does suffer with use are the additive packages added to the oil. Synthetics are no different. Engines that see only limited use and ones that may never get up to full operating temperature can suffer from high levels of contamination that will require shorter drain intervals.