In the last years no brand got such a fame and sudden credibility like Royal Purple did, and much of it thanks to their line of motor oils. The Royal Purple 5W-20 though is responsible for a lot of this success, highly rated on several customers and specialist’s list,it is also the most sold synthetic oil on several different web stores, from Walmart to Amazon. Let’s take a look on the pros and cons of this formula and what makes it so popular.

Royal Purple 51530 API-Licensed SAE 5W-30 High Performance Synthetic Motor Oil


To sum up the oil before we get to talk about in details of our Royal Purple synthetic oil, we can point out these basics about the formula:

  • Thin, light oil, ideal for vehicles on cold weather
  •  Works with gasoline and diesel engines
  • Has some compatibility with ethanol based vehicles that use fuels up to 20% of ethanol
  • Wear performance avoids metal-to-metal friction
  • Improved performance of green emissions by the catalyst system
  • Oil drain intervals are up to 10k miles after the break transitions
  • Highly solvent, removes deposits from old oils stored in the engines


  • While many motor oils are quite specific about the type of vehicles that are compatible, Royal Purple creates some quite versatile formulas. This series of SEA oils are recommended for both diesel and gasoline vehicles, as well as passenger cars and light trucks. On the other hand, all this versatility is not that much accurate. Some vehicles might need something stronger, especially because they might be way too much for this oil to improve the performance since it has a quite low viscosity. There is not an official list of the kinds of cars that could fail with this 5W-20, but the most simple the car is, the more likely it will have problems of performance since their engines require more viscosity for wear performance.
  • The issue here is not because this oil has any issues, it simply is developed for cars that require less viscosity. If you car needs something with higher viscosity there are other degrees available of the same line, like 15W-40 or 20W-50.
  • Mind that oils of such low degree are ideal for cars that work on cold weathers. If you live in Miami you’ll never need a oil whose start engine viscosity is so low. The less viscous, the more easily your vehicle will start on low temperatures, on the other hand, a thin oil like this will turn into water on hot weather and offer a poor wear performance.


While many oils might have a lot of fancy, patented substances to it that hardly really make a difference, this AP1 5W-20 has only two essential and simple additives that make it what it is:

  • Increased wear performance avoiding friction between dexos1™* and ILSAC GF-5 specs. This wear performance will also increase the fuel performance since there is less friction and the engines will run smoother, with no stronger efforts – and consequently more fuel burning – since the motor can work better.
  • Addition of pattented ZDDP additives that will optimize the life of the emissions catalyst system, which is responsible for converting toxic pollutants in exhaust gas to less toxic pollutants

In addition, there is nothing official in the label of the product about it but this oil is also sold as a “Improved compatibility with fuels containing ethanol”. This might be tricky and a matter of trying and testing as it seems. Royal Purple tested the oil with ethanol based engines and noticed it causes no “white sludge and lubrication starvation that can occur with 20% or higher ethanol fuel”. In other words, it is less than 80% efficient for ethanol based cars because it will work only under a 20% ratio and will prevent rather then completely protect it against these issues.


  • As a synthetic oil with no expiration date, this SAE 5W-20 can work for a long while, but if you are constantly circulating with your vehicle, each quarter of it will last for up to 10k miles.
  • The brand however has some recommendations when it comes to change from oils of other brands to the SAE 5W-20. The instructions are to wait until the next oil change scheduled for your car to do the transition or, in car recently new, apply the new oil after 2.000 miles in new gasoline engines. For diesel vehicles, like trucks, you have to ride your car for 8 to 10k miles before the change.
  • Doesn’t matter how much old your car is, the Royal Purple oil will work as well and even perform the dissolving of many residual elements inside in the engines. It is also recommended that your vehicle perform two short breaks, one of 3000 and another of 5000 miles before you extended the oil drain intervals to the official interval of 10k.
  • This is recommended so your engines work as perfectly as possible. As a synthetic oil, the Royal Purple oil will perform a gradual removal of the deposits.


The 5W-20 is rated 5 stars on sites like Amazon, based on the reviews of over 200 different buyers. Most costumers praise the silent performance the oil provides to their engines and the highly effective performance on gas mileage. This formula was first released in 2009, when it used to be much more expensive. This is the major complaint of many buyers until the release of the 5W-30, which got more attention, salty prices as well as criticism. Then the 5W-20 started to be sold on promotional sale. While the quality of the oil didn’t change, you can easily find it with at least 40% discount compared to the launch prices. Each quarter nowadays cost around only $8, and you can find it both on single units or packs of 5 to 6 quarters or gallons.

Royal Purple 36140-6PK HPS 10W-40 Synthetic Motor Oil with Synerlec Additive Technology