Choosing which oil you should use for a portable generator can be just as confusing as choosing the right paint for a room, the choices are so abundant that it can be difficult to even know where to start looking.
You should use either a 4 stroke 10W30 (or 10W40) oil or an SAE 30 oil in your 4 stroke generator unless the generator’s operation manual specifies otherwise. Some generators will also be able to use a synthetic 5W30 oil which is ideal if you are using the generator in colder temperatures.
** It’s worth noting that all generators should come with a user operation manual. It’s best practice to reference the user manual first as this should give an indication of what oils are not only safe but also optimal to use in your generator.
The standard oil recommendation for most 4 stroke generators is a specific 4 stroke 10W30 oil. There is a range of factors that influence what types of oil your generator can take and in this article, we’ll cover a few of these factors to ensure you use an oil that will give the best efficiency and value.
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Why Does a Generator Need Oil
Most portable generators are not too dissimilar from car engines and this often leads people wondering if they can use car oil in their generators.
It’s important to note that all generators will have an operation manual which will specifically state which oils are suitable for your specific model. You can also look online for your brand’s manual but never make the assumption that your generator can function with any and all oils.
A generator needs oil to function and provide the initial power, it ensures that all parts are working properly and essentially ensures that your generator can produce power to run. Therefore, if you want optimal performance and longevity then you’ll want to use the most suitable oil that you possibly can.
Price should not be a determining factor in this but rather opt for a specific type or brand of oil that you should use because not all oils are the same.
What Oil Should You Put in a 4 Stroke Generator
For a 4 stroke generator, you’ll want to use a specific 4 stroke 10W30 oil as standard, though as always we need to emphasize that you must check the operating manual specific to your generator to see what the recommended oil is.
This is because you’ll need to consider the type of oil used in terms of viscosity, temperature and brands so we’ll quickly look at each factor now.
The viscosity is closely linked to temperature and is the letter and number system used for the oil that you’ll see on most packaging (SAE 10W30 as an example).
SAE is the grading system that refers to the viscosity of the oil at different temperatures. Using the example above, 10W is the first part and refers to the temperature at which the oil can be pumped in cold temperatures and the ‘W’ stands for winter (not weight which is often confused).
The second part which is 30, is how possible it is to pump the oil when heated to temperatures at 232°F or more.
As you can see, a synthetic 5W30 will run at a broader range of temperatures than a 10W30 so keep these numbers in mind when looking at the temperature that you’ll be running your portable generator on.
The temperature that you’ll be using your oil in is also a key factor to take into consideration when it comes to choosing your oil. The below guide should be used to help you choose the most suitable oil for your generator:
- Temperatures above 32°F > Use an SAE 30 oil
- Temperatures below 40°F down to -10°F > Use a 10W30 oil
- All temperatures > A synthetic 5W30 can be used in all temperatures
Branding is something that’s surprisingly very important when it comes to engine oil, we can assure you that an established brand known for producing high-quality oil is almost essential for a portable generator.
This is because a relatively unknown brand using poor quality oil could potentially damage your generator and the cost of repair or replacement will be significantly higher than going with a well-established brand from the start (besides, the cost difference really isn’t that much between the main brands).
The following are some of the products that you should consider from reputable brands that cover all of the main requirements:
SAE 10W30 Oil – Castrol 03093 GTX 10W-30
SAE 30 Oil – Generac 6840 Maintenance Kit for Portable Generators
Synthetic 5W30 Oil – Briggs & Stratton SAE 5W-30 Synthetic Small Engine Motor Oil
It’s also worth mentioning that Honda, Shell and Valvoline are other top brands in terms of engine oil and all have similar products to the ones listed above.
Can You Use Synthetic Oil in a Portable Generator
When it comes to engine oil, you can use either conventional oil or synthetic oil depending on the operating manual guidelines.
Synthetic oils are a premium blend with many designed specifically for 4 stroke engines and could, therefore, be the best option for your portable generator. They function in a wider range of temperatures and are generally higher quality but you’ll need to be prepared to pay a slightly higher price.
How to Insert Oil Into a 4 Stroke Generator
Adding oil to your generator is a simple and quick task so try not to overthink it. We know this can be a bit daunting if this is your first time using a portable generator and the last thing you want to do after purchasing an expensive generator is pour oil into the wrong compartment!
To add oil, keep your engine right side up and locate the oil cap (this will be a different compartment to the fuel cap so keep that in mind). If you are having difficulty locating it then just refer to the user manual for help.
Unscrew the cap and fill with oil using a funnel to the marked fill line which is typically around 600ml for smaller portable generators. Once you’ve filled it the fill line screw the cap back on and you’re done, it’s really that simple.
Just note that we never recommend pouring freehand without a funnel, spillages are not only a hassle to clean up when it comes to oil but you also don’t want it getting into parts of the engine where it shouldn’t be as this could cause operating complications.
How Often Should the Oil Be Changed in a Generator
To ensure the efficient and smooth running of your generator you should perform an oil and oil filter change 20-30 hours after first use and then after every 100 hours of run time from the second use onwards.
With synthetic oils, you’ll be able to double that time and perform an oil and oil filter change after every 200 hours of use.
There are a few factors that you might not have been aware of previously when it comes to selecting an oil for your 4 stroke generator. Your first action should always be to check the user manual that is specifically for your model of portable generator as this will tell you exactly which oil you should use.
In most cases, however, a 10W30, SAE 30 or synthetic 5W30 will be suitable for most models and always try to purchase your oil from an established brand to ensure that you are getting a quality product.