Generator Oil Matters: Choosing The Right Oil For Your Generator

You may be guilty of thinking “oil is oil” and never give much thought about what you are putting into your generator’s oil reservoir.  Not many of us consider the oil in our smaller engines.  You push the limits of how often you change the oil in your car.

However, it’s likely that you have never “changed” the oil in your lawnmower.  Oh sure, you may check the oil, and top it off if it’s low. But, most people simply don’t think much about small engine oil changes. Generator oil is one example of this.

What Does Your Generator Oil Do?

This mentality has to change when you purchase a generator.  Generator oil is the same as any other engine oil. There is no particularly special formula. Also, you won’t see too many products labeled “generator oil” on the shelf (though there are a few).

Generator oil IS just standard motor oil. But, most common generator failures can be traced to improper maintenance and a severe lack of understanding on how the generator engine uses oil.  You should be regularly changing the oil in your lawnmower. However, you absolutely must be on top of the oil situation in your generator. Otherwise, you will start having troubles that may lead to a non-functional unit.

generator oil

The “generator” part of your generator is an electrical part being turned by a mechanical engine.  Half of your machine is a simple four stroke engine. This is the same concept as your lawnmower or your car.  Two-stroke engines, such as what you may find on your weed eater or mini-bike, mix the oil in with the fuel.

You won’t find many generator engines that have this feature.  Most have a fuel tank and a separate oil reservoir.  Your generator oil works the same as what you may think of as a “standard” internal combustion engine.

Our Top Five Recommendations For Generator Oils

Diving into the importance of a properly-oiled generator

An engine’s piston is cranking away up and down thousands of times per minute. With each turn, it is compressing fuel and sparking a minor and controlled explosion. This thrusts the piston into another cycle and turns the crankshaft. This, in turn, is what turns the electricity producing piece of the generator itself.

However, with all that movement, there is a significant amount of waste created in the friction between the metals and the byproduct of heat.  Engine oil lubricates these parts to reduce the friction and the cycling of oil in and out also absorbs some of the heat as well.

Generator oil maintenance is a necessity because while most small engines run hot and fast, generators are always pushing their limits the more you draw on them.  Think of it like this; When you run your generator without connecting a load, the oil is doing its job.  As soon as you connect an electrical load, the engine ramps up and your generator’s oil is having to work overtime.

If you don’t watch your generator oil levels, and change it out often, the oil will eventually break down and become less efficient. Alternatively, it may burn off and eventually lead to your engine’s piston. Without the essential lubrication and cooling required to keep it running, this can be catastrophic.  This will lead to a seized engine which will not only leave you in the dark, it may leave you without a generator!

Reasons You May Need A Different Generator Oil

When you unpack your brand new generator from its shipping crate, you may find a bottle of oil included with the accessories.  Some manufacturers are generous enough to send you everything you need to get started (except for the gasoline of course…)  In the owner’s manual there will be a detailed section on your generator’s oil capacity and filling location.  Inside this section, the manufacturer will suggest the proper weight oil to use for this machine.  In most circumstances, it really as simple as following the manufacturer’s recommendations.

However, there may be situations where it would be wise to change the weight of your oil for prolonged use in adverse conditions.  Generators being one of the tools we are most likely to use during “adverse conditions”, knowing the proper generator oil for your situation is something you should be aware of ahead of time.

Measuring oil weight and properly using

Oil weight is measured by a term called viscosity which is easily compared to the oil’s “thickness” and its resistance to flow.  Water runs downhill rapidly and has a low viscosity index around 0.8.  Honey creeps downhill incredibly slow and has a very high viscosity index in the range above 2000.

Motor oil should be thick enough to keep the engine parts lubricated while remaining thin enough to move around inside the engine.  Making this task even more difficult is the property of oil losing viscosity when it is heated.  So your manufacturer has done all the hard work for you and picked out the right generator oil for your machine, probably something around a 5W-30 which means it has a VI of 5 in cold weather, and a VI of 30 in hot weather.

Where you may need to change which generator oil you use is in your climate or extreme use.  If you are operating your generator in a remote desert, or even in the scorching sun of a hot Florida summer after a hurricane, the unrelenting heat may call for a higher weight oil such as a 20w-30 to thicken the oil up.  And if your generator is getting the most use during winter blizzard conditions on a rural mountain, you may need to go with a lower VI such as a 5w-30 to keep the oil thinned out.

Standard or Synthetic Oil In Your Generator?

One final question you may have about generator oil is whether to use synthetic oil or not.  There is a regular encampment on either front where some claim synthetic oil is always better than standard. Conversely, the other side claims synthetic is a fraud and you don’t need it.  Both sides have valid arguments.

Synthetic oil is good for aging engines as it doesn’t break down as quickly.  This will prolong the life of the oil and protect your generator but the other side of the argument holds that it doesn’t allow your engine to “break in” properly and you will begin to burn off oil at a much faster rate than normal.

Using synthetic oil for a generator engine can be good. But, it should also be overkill because you should be checking and changing that oil regularly.  By the time the benefit of having synthetic oil comes around, you should be changing it out anyway.

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