Generator Leaking Oil? Causes and Solutions7 min read

I think that generators are essential tools: they’re amazing for power outages, as well as powering outdoor appliances. I find them a really handy tool to have around for emergencies. Unfortunately, like any other device, generators can develop problems over time and even stop working completely.

Chances are, if you’re having problems, oil leaks are the culprit. But what can you do about it?

Generator oil leaks can be caused by damage, aging parts, loose fittings, overfilled reservoirs, and damaged seals or gaskets. You can fix this by turning off the unit, identifying where the leak is coming from, and tightening or replacing parts.

I always say this up top, but it’s worth saying again: if you don’t have the experience or tools for this repair, don’t go ahead with it. Call a professional instead! That’s what they’re there for, and safety is the number one priority. 

Mark Longhurst, a plumber with over 15 years of experience and owner of Pipe Smart, works with generators regularly and has reviewed this article for us. We take reliable information seriously, so look out for expert quotes throughout!

Why Is Your Generator Leaking Oil? 5 Causes and Solutions 

Generators typically use gasoline or diesel engines. They’re ideal for powering outdoor activities. If you have a big backyard that needs a lot of TLC, a generator is perfect. I used mine a lot when we moved into our new property, and the yard needed a ton of work.

I have a large Honda wheely generator like this one.

But oil leaks are a pretty common issue. Over time, though, they can stop the generator from working. Here are what I think are the most common reasons for leaks:

1. Aging Parts

There are a few different mechanical parts of a generator, and these can wear down over time. In my experience, it’s the little parts like seals, gaskets, and hoses that are more prone to damage. I always check these parts to see if there’s a problem as a priority.

If these parts become brittle, they can crack, which allows oil to slowly escape from the unit. Not ideal!

2. Wear and Tear

Pretty similar to the last point, but wear and tear can cause leaks to appear. Parts like pistons, bearings, and crankshafts are put under stress with high pressure and heat, and although they’re pretty tough, they just don’t last forever.

3. Overfilled Oil Levels

It’s easily done, but sometimes you can get a bit carried away with oil filling. If you add too much oil, it can overflow and leak out. I know this from experience – I maintain my motorcycle and overfilling it with oil can actually cause significant problems to the engine.

Try to stay within range to stop any accidental leaks, and you should avoid those annoying oil spills on your clothes.

4. Loose Fittings

I always say if there’s a problem with any kind of appliance or tool, check the fittings and connections. These are prone spots to wear and tear, and in generators, they can cause oil leaks. It’s the first place I check when something of mine breaks down.

The fitting that attaches to the oil lines and hose can become loose over time, which can cause oil spills. Luckily, this is a quick fix – just tighten them as soon as you can, and the problem should be solved. I think many people can handle this level of maintenance, and I find it doesn’t take long.

5. Damaged Gaskets or Seals

The last common culprit that I’ve had problems with is the gaskets and seals. These are the parts that create a tight seal between components, preventing oil from escaping. But after a while, they just wear out, causing a leak.

Also, poor quality or incorrect oil can cause real damage to your generator. Poor quality oil, or the wrong type, can have a different viscosity and can cause damage to the seals, causing oil to leak.

This can void your warranty. I know it’s tempting to use cheap oil, but it can cost you way more cash in the long run, so I’d recommend avoiding the cheap stuff. Go for the recommended oil, suck up the cost, and know that you’re making the right decision in the long run.

Other Signs Your Generator May Be Leaking Oil

How can you tell if your generator is leaking oil? I’ve been there before: here are a few signs you need to keep an eye on.

Oil Stains or Puddles

Oil stains are pretty noticeable. If you see a leak under the unit, chances are you’ve got a problem.

This is really important to take care of right away. If you have a power outage, you might need that generator. Plus, in my experience, oil stains are really tough to remove and require quite a lot of scrubbing (that’s if you can remove them at all).

I have experience working with generators, and fixing them can be tricky depending on what the issue is. The first thing to do is conduct a thorough inspection just by looking, focusing particularly on gaskets and seals for wear and tear, or any loose fittings. Broken or damaged components can be replaced pretty quickly.

Mark Longhurst

Unusual Sounds or Vibrations

If your generator makes weird sounds or vibrations while you’re using it, the problem could be an oil leak somewhere.

Leaking oil can cause some friction between the different moving parts of the engine. This can cause rattling or vibrations that feel and sound weird when you use it. If this is the case, switch it off right away and take it for repairs.

Oil Levels Dropping Faster Than Usual

I was using my generator recently and noticed myself topping up the oil more quickly than usual. I was super busy, so it was easy to kind of forget about it, but eventually, I remembered to check. This was a good call: it turned out I had a small but noticeable leak.

Maintaining the optimal oil levels is really important if you want your generator to perform properly. If you do notice oil levels dropping, it’s important to stop, switch it off, and check it out. There might be a small leak somewhere, so check around it for clues like stains or dampness.

Mark Longhurst

Burnt Oil Smells

This is a pretty obvious one. If you can smell a foul, burnt oil smell, chances are it’s an oil leak. When it comes into contact with the engine, it will cause that weird burning smell. If this happens, you’ll need to get it repaired professionally.


Your generator shouldn’t get super hot while you’re using it, and overheating could point to a leak problem. The excess oil can cause friction, which can lead to the unit getting super hot. Switch it off right away if this is the case and see if you can locate a leak. You might need to call a professional here, too.

How to Fix an Oil Leak in Your Generator

I would say that an oil leak is not something to panic about. I’ve dealt with worse, and I’m sure you probably have, too. There are steps you can take to deal with it. Here’s what I’d recommend:

Step 1: Shut Down the Generator

This is the most crucial first step. I know I always talk about safety, but it’s really vital. Don’t just switch it off and jump right in, either. You have to wait for it to cool down first to be able to safely handle the components.

Step 2: Locate the Leak

Now is the time to find the leak. Look at the engine and try to find oil stains or puddles; that might give you a clue as to which area the leak is coming from.

It’s such a basic thing to keep in your toolkit, but a flashlight will help you to see clearly, especially if you’re keeping the generator in your basement.

Step 3: Replace Damaged Parts

Now’s the time to get rid of any damaged gaskets or seals. You should be able to spot them if they’re damaged enough to cause a leak.

In my experience, a local hardware store is the best place to check, but you may have to order online from the manufacturer if you can’t get a hold of the right part. Check the instructions to make sure you’re getting the correct parts.

Step 4: Tighten Loose Fittings

Loose fittings are a pretty easy fix. Just tighten them up using a wrench. As always, check the instructions from the manufacturer first so you’ll be using the right equipment.

Step 5: Refill the Oil Levels and Inspect

Now is the time to refill the oil levels to the recommended levels. As I mentioned earlier, use the right oil – it’s honestly worth it!

Now you can power up the unit and watch for leaks. If the leaks are cleared up, you can use it as normal.

What Are the Risks of Ignoring an Oil Leak?

With something like a generator, which you don’t use every day, ignoring any problems is really easy to do. Life is busy, and if you’re anything like me, you’ll have a million jobs on your to-do list.

But oil leaks can cause way more problems to add to your list, and here are a few of them:

Fire Hazards

Oil leaking out and coming into contact with the engine can ignite, causing a fire. This is obviously a severe problem. Oil leaks can also cause the exhaust to overheat, which, again, can cause a fire hazard.

Damaged Engine Parts

Oil leaks can cause all kinds of issues with engine components. Getting these replaced can be expensive, and in the worst case, you might have to buy a whole new one instead.

Generally, leaking oil can increase the wear and tear on the engine, causing it to fail quickly. I was glad I caught mine early, but if I hadn’t, I may have had to replace the whole thing.

Decreased Efficiency

Your generator just won’t work as well if it’s leaking oil. Oil leaks make the whole thing work harder than necessary, and it will use a ton of fuel to work, which means you’ll end up spending more money on fuel too.

Prevention Tips

Prevention is better than cure. Looking after everything in your home is overwhelming (I know that I forget things sometimes too), but a little maintenance really helps to prevent leaks.

A few steps I think you should take to prevent leaks include:

  • Regular maintenance and inspections: This can prevent issues before they arise and keep your generator running smoothly.
  • Monitoring oil levels: This will help you detect any potential leaks or problems early on.
  • Changing oil filters and oil regularly: This can prevent buildup and ensure your generator operates efficiently.
  • Proper storage and transportation: This includes keeping your generator covered and avoiding rough handling during transport, which can prevent damage to your generator.

When to Call a Professional

Sometimes, your own efforts just aren’t enough. Professionals can take care of the job for you, and it’s important to call if your own elbow grease isn’t working out. I call professionals all the time for stuff at home, even though I love fixing things myself – even I know when to admit defeat sometimes.

In my experience, you might call a pro if:

  • Your generator is still leaking oil after troubleshooting and repair attempts.
  • Your unit is still under warranty.
  • Your generator has complex components, and you don’t have the knowledge necessary.
  • Your generator has significant oil leaks or engine damage.
  • Your unit has a carburetor or fuel system issue.

Frequently Asked Questions

Before you go check out your generator for leaks, here are some questions you might be interested in:

What Type of Oil Should I Use In My Generator?

Generally, generators require a specific type of oil, such as 10W-30 or 5W-30, depending on the temperature range and engine design.

However, the type of oil you should use in your generator depends on the manufacturer’s specifications. Consult the owner’s manual or the sales engineer for your generator’s brand, and they’ll be able to tell you the recommended oil type and viscosity.

Can I Use a Leak Sealer to Fix the Leak?

While some leak sealers may temporarily fix an oil leak, it’s not a recommended long-term solution. Leak sealers can cause damage to your generator’s engine, and the sealant can clog or damage critical engine components. It’s best to address oil leaks properly by fixing or replacing the damaged parts, in my experience.

How Much Does it Cost to Repair an Oil Leak in a Generator?

The cost of repairing an oil leak in a generator depends on the severity of the leak and the type of repairs required. For minor leaks, the price may be relatively low, ranging from $50 to $200, while significant leaks or engine damage can cost quite a lot more.

How Often Should I Change My Generator Oil?

Generally, it’s recommended to change the oil after the first 20–30 hours of use and then every 100–150 hours after that. 

Oil changes can be done by anyone, but it’s better to consult your sales engineer for the proper maintenance. They can schedule a regular check up, which includes taking care of oil. If you want one less thing on your plate to deal with, I’d recommend doing this.

Generator Leaking Oil: Key Takeaways

If your generator is leaking oil, it’s annoying, but it could be fixable at home. Signs like oil stains, burning smells, and weird noises and vibrations are all key signs that something is wrong.

In my experience, you can fix leaking oil by:

  • Shutting down the generator first (this is a really important safety measure!)
  • Locating the leak by following oil stains or drips
  • Replacing damaged gaskets or seals, which are the most obvious culprits in my experience
  • Tighten loose fittings or connections using a wrench, but check the owner’s manual first
  • Refill the oil levels back to normal and check it to see if it’s running properly
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Hi, I'm Ed, and I run BuildFanatic! I enjoy providing the best possible information on a range of home improvement topics.

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