Buying The Right Oil For Your Generator: Synthetic vs Regular


The importance of motor oil in the operation of generators is one that is well-known. For this reason, you should be concerned about the type of oil you use in your generators. A common question that keeps popping up from generator owners is about the use of synthetic oils in generators. We’ll be answering this question in this article. 

Can you use synthetic oil in your generator?

You can use synthetic oils in newer generators. Synthetic oils are better at lubricating your generator and can extend engine life. Quality synthetic SAE (5w30, 10w30) oil from brands such as Castrol, Pennzoil, Generac are good choices. Older generators should not use synthetic oil as it can loosen engine deposits and cause damage.

Using the wrong kind of oil in your generator can shorten its lifespan or even cause complete engine failure. Continue reading to learn more about synthetic oils and why they are great for your generator.

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Using the right synthetic oil

Different generators may require different types of oil. Manufacturers usually specify the viscosity number of oils that’s compatible with their generators. It’s important to use synthetic oils that have the viscosity number specified by the manufacturer. 

Viscosity number is an index of how well the oil resists flowing. For diesel engines, viscosity is a little more complicated because the flow of the oil is dependent on the temperature of the engine (hot or cold) and oil needs to be able to flow adequately in both situations. Higher viscosity numbers mean the oil is better able to resist flow. 

You’ll find out the viscosity number for engine oil is usually made of two figures, say 10W-30. The first number with the ‘W’ (winter) Is an indication of how well the oil will resist flow or thinning at 0°F (about -18 degrees C). Since the W is for winter, the number is talking about the resistance of the oil to thinning in cold weather. And the lower this number is, the lower the tendency of the oil to thicken in the cold.

Synthetic oils generally make great winter oils and should be used by people that operate their generators during cold winter months. 

The second number refers to the performance of the oil in hot weather – 212 degrees F, (100 degrees C). The higher the number, the less the oil will thin out in hot weather and vice versa. So, you can expect a 10W-30 rated oil to thin out faster than a 10W-40 rated oil in hot weather. 

Temperature Guide for Oil Types

If you plan to operate your generator during extremely cold temperatures or the thick of winter. I would recommend using a 5w30 oil. This viscosity oil remains thinner in colder weather, making it great for cold start ups. It also works great during hot summer weather. Overall its a great oil for generators.

I recommend using Castrol 5W-30 Advanced Full Synthetic Motor Oil for your generator. You can find it on Amazon here.

TemperatureOil Type
0° – 100° F5W-30
55° – 100° F10W30

Why synthetic oil is good for your generator

The base oils used to manufacture synthetic oils are generally of better quality than those used to manufacture conventional oils. It is the higher quality of these base oils that make synthetic oils more chemically stable and a lot more difficult to break down and lose their desired properties. 

Thanks to the complex process of making synthetic oils, they also contain fewer impurities than conventional oils and can be tailored to meet specific demands of modern oils. This is why synthetic would offer better engine performance than conventional oils. Other benefits of synthetic oils include:

Greater engine protection

One of the functions of oils in engines is to protect the parts of the engine that are in contact with one another. Using synthetic oil will provide better protection for your engine as they don’t break down like conventional oils do. 

Cleaner engine

Deposit forms as the oil in your generator circulated through the engine. Using conventional oils will result in the formation of sludge which will accumulate over time ultimately reducing the efficiency and lifespan of your engine. However, synthetic oils have less tendency to form sludge as they contain fewer impurities. 

Better viscosity

Synthetic oils offer better stability and viscosity at both high and low temperatures. The ability of synthetic oils to flow quickly in cold temperatures while also resisting extreme heat is beneficial to the smooth running of your generator in winter and summer. 

Does synthetic oil last longer than conventional oil?

This is another frequently asked question about synthetic oils. And the answer to this question is a solid yes. You can expect longer intervals between oil changes when running your generator on synthetic oil. However, the brand of synthetic oil you are using also comes into play. 

Check the manufacturer’s recommendation regarding oil change intervals. You may also need to change your oil more frequently when you are switching from conventional oil to synthetic oil because the engine probably has a buildup of deposits and sludge.

Synthetic oil is worth the extra price

Synthetic oil is more expensive than conventional oil but it’s totally worth the extra price.

The reason for the increased price of synthetic oils compared to conventional oils is due to the presence of additives like detergents, anti-wear agents like zinc dithiophosphates, and many more. It is these additives that improve the performance of synthetic oils and increase their lubrication and cooling properties. 

On the other hand, conventional oils generally have a much lower amount of additives. This is because their base stock is typically of lower quality and adding expensive additives to a poor base is simply not sensible. 

There is a myth that it’s harmful to change from conventional oil to synthetic oil. The same myth also states that a “break-in period” is required to make the switch. This isn’t true. You can change from conventional oil to synthetic oil at any time. 

However, if you are concerned about the extra cost of synthetic oils, you can use conventional oils in your generator when it’s new. You’ll have to eventually switch to synthetic oil as the engine ages to improve its longevity. But if you can, always use synthetic oils in your generator. And once you choose a brand of synthetic oil, stick to the same brand. It’s not advisable to regularly change the brand you are using as all synthetic oils aren’t exactly the same.

Check out the best generator oils on Amazon here (affiliate link).

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