In fact, the right oils for generators are the same synthetic motor oils you use for your car.
Any good quality synthetic 5W-30 oil will be a good choice for your generator.
Taking this into consideration, we think that Castrol 03084 EDGE 5W-30 is the best fit for most generators.
It is one of the best performing synthetic oils suitable for car and generator engines.
Keep reading if you want to learn more about what makes some oils better than others and how to these affect your generator engine.
How to Choose the Right Oil for a Generator
When buying oil for your portable generator you should take into account a few important considerations. Follow these steps to get a better idea of what exact kind of oil you need.
1. Read the Manual
This is the first and probably the best step you can make before purchasing oil for your generator. Every portable generator comes with the user’s guide. The manual section of this guide about generator maintenance should mention what exact kind of oil does your generator engine need.
2. Determine the engine type
Different engine types demand different types of oil. The good news is that the vast majority of generators are equipped with 4-stroke engines making the choice easier. You won’t find many generators with 2-stroke engines.
The most common oil used with 4-stroke engines found in generators, lawnmowers, and other related equipment is SAE 30. You can also go for its synthetic variations such as SAE 5W-30 and SAE 10W-30.
3. Operating temperature
This are the criteria you should take into account if you are planning to run a generator out in the cold. Certain types of oil are specifically designed to be used in extreme temperatures. Then there are oil types that generally support a wider range of temps. One such oil is SAE 5W-30 which is suitable for engines exposed to as low as -20F. Conversely, 5W-30 is also good for higher ranges of up to 100 degrees.
4. Check the Viscosity
Talking about temperatures, this is the exact oil feature that determines how suitable the certain oil type is for cold weather. It basically represents the fuel’s resistance to flow. You can easily find out the viscosity by simply looking at the name of the oil.
The first number before the letter “W” (as in “winter”) is the viscosity at 0 Fahrenheit. The second number represents the value at 212F.
Generally speaking, for hot temperatures the higher the second number is, the better. It means that the oil is thicker and provides enhanced lubrication for the moving parts of the engine.
On the other hand, if you are primarily intending to use the generator in the cold surroundings then you should pay close attention to the first number. That’s why as we’ve mentioned before, the SAE 5W-30 is a better choice for sub-zero temperatures.
5. Stick to reputable brands
You should only buy oil manufactured by trusted companies. These should be approved by the Society of Automotive Engineers (SAE). Some of the most reputable names include Castrol, Shell, Generac, and Schaeffer. Check out the listings on Amazon to ensure you only buy the quality oil with good reviews.
Our Selection of Best Oils for Generators
1. Castrol 03084 EDGE 5W-30 Advanced Full Synthetic Motor Oil
Castrol 03084 EDGE is a premium full synthetic motor oil made to be used under high pressure. It’s one of the best synthetic oils available on the market. It performs very well in extreme temperatures, significantly reducing friction between moving parts of the generator engine. It has all required certifications issued by American and international automotive regulation bodies including API SN, ILSAC GF-5, ACEA A1/B1, A5/B5 etc. Its design incorporates fluid titanium technology which has a positive physical impact on how the oil reacts to the highest pressure. Overall, this is one of the most popular motor oils in the market and IMHO is the best choice for portable generators.
2. Shell Rotella 550045348 T5 15W-40
Shell is a very reputable automotive brand manufacturing highest quality fuels and engine oils. Rotella is a very durable and robust engine oil, performing on average 37% better than the max wear requirements stipulated by API CK-4 tests. It features a Triple Protection Plus technology which further helps minimize friction inside an engine. It also offers additional protection against oil breakdown. Overall this is one of the top-performing engine oils suitable for a typical 4 cc generator motor.
3. Pennzoil Ultra Platinum Full Synthetic Motor Oil 5W-20
Pennzoil produces high-quality synthetic oils suitable for lower temperatures. It can easily handle temperatures as low as -13 degrees Fahrenheit. It usually performs very well in the whole variety of tests. It has a SN/GF-5 certification. This oil is also known for providing the additional layer of protection to the engine parts, significantly enhancing their lifetime. It comes highly recommended to all portable generator owners.
4. Generac Full Synthetic Motor Oil 5W-30 SN
Generac is the name very well known in the generator industry. Their generators, both standby, and portable, are among the most popular on the American market. Therefore it doesn’t come as a surprise that the Generac motor oil is also a very good choice to use along with portable generators. It is specifically designed to work within the wide temperature range, from subzero freeze to tropical heat. You can also totally use it with the standby generators (not only the Generac ones). Bear in mind though that if you want to use it with larger generators you should stock larger quantities in advance (the same can be said about other oils). One quart is certainly not going to be enough to run a whole house generator for a long time.
5. Schaeffer 9003D-012S Supreme 9000
Schaeffer is another very trusted brand in the automotive industry. The motor oil released by this reputable manufacturer performs flawlessly in different settings including the below-freezing temperatures. It is blended with friction modifiers that give better protection against scuffing or abrasion. It is also GM dexos-1 compliant. As long as you follow the instructions provided by your generator manufacturer and apply this oil on a regular basis, you can expect it to preserve your generator motor for years to come.