Is Starting Fluid Bad for Gas Engines?

The simple answer: In small doses and used properly, it can be effective in hard-starting gasoline engines. But it can be bad for two-stroke or diesel engines. The real question to ask is, “Why does my engine need starting fluid in the first place?” Find out the answer, then fix the real problem.

The detailed answer: Ask five gearheads or mechanics their opinion of starting fluid, and you might get five different answers.

Some occasionally use it to help revive an engine that’s been pulled from storage. Others use it to help coax a stubborn engine to life on a frigid morning.

Warnings against using starter fluid

Yet others won’t touch starter fluid.

One mechanic I talked to blamed it for ruining the bearings in a two-stroke outboard motor. Its owner, the story goes, liberally sprayed starting fluid into the intake when the engine wouldn’t start. And sprayed. And sprayed.

Starting fluid typically contains ether, which is an effective solvent. In this case, the starting fluid washed the inside of the engine clean of oil, allowing metal components to contact and eventually seize.

Diesel engines, too, can suffer the effects of starting fluid. Their high compression can cause the fluid to ignite too early, effectively causing pre-ignition, which invites all kinds of problems, like catastrophic piston or rod damage. Plus, it has no lubricating properties, so it can hasten piston wear.

With minimal work, you can find all sorts of cautionary tales on the Internet of people blowing up engines after using too much starting fluid.

Starting fluid does work (sometimes)

Given the disdain many harbor toward starting fluid, why would anyone use it?

Because it can be effective in gasoline engines – especially carbureted engines – when used as directed.

For gasoline to combust, it must first be vaporized. The fuel injectors in your car or truck do a great job of completing this task.

In carbureted engines, fuel is vaporized as it’s forced through the tiny openings or nozzles in the carburetor. But carburetors don’t vaporize fuel as effectively as fuel injectors. Plus, gasoline doesn’t vaporize as readily when it’s cold. Anyone who’s started a carbureted car on a frigid morning knows this all too well. Plus, an engine requires more gas in the fuel/air mixture at startup, making a cold engine doubly difficult to start and keep running.

Starting fluid, on the other hand, does readily ignite in the cold, helping to start the engine and generate heat to more easily vaporize the fuel.

But a little goes a long way. Many of the problems with starting fluid can be attributed to operator error rather than the fluid itself.

In short, if you have to use starting fluid, use it sparingly. If a couple short bursts of spray into the intake don’t elicit a cough or two from the engine, emptying the can isn’t going to work, either.

Small Gas Engine Repair
No amount of starting fluid is going to revive an engine with a dirty carburetor. Identify the real problem and get it fixed.

Figure out why you need starting fluid in the first place

Instead, ask yourself why the engine needs starter fluid in the first place. There’s likely a bigger problem that needs fixing.

I was presented with this exact scenario when my snowblower refused to start. So I reached for a can of starting fluid and gave the intake a shot. She sputtered a few times and quit. I repeated the process a few times, with the same result.

Eventually, I took apart and cleaned the carb. She roared to life on the first pull after that.

In my case, emptying the entire can of starting fluid into the engine wouldn’t have done a thing, aside from washing the oil from the cylinder and causing wear. At the very least, it helped me diagnose what the problem was not: lack of spark or bad compression.

The bottom line:

Starting fluid can help start a stubborn engine, but follow the directions and use it sparingly. If a little bit doesn’t work, a lot likely won’t, either. If your engine is consistently hard to start, find out why and get the real problem fixed.

Updated. Originally published: May 22, 2017.


  1. I have a generator that runs great but is hard to start if idle for several months. I always use fresh stabilized gas. One quick squirt of starter fluid gives me a start with one or two pulls. Then it starts ok there after until another long storage period. I think the rubber push pump to prime the carb does not work properly.

  2. I stay away from starting fluid, however if I have an engine that is temperamental in the cold or first start of the season I will give it a shot of Power Foam. Wakes it right up and doesn’t peal the lube off the cylinder walls like starting fluid.

  3. Used to feed cans to the old 80s cat rock truck at -30 here in northern Ontario never had a problem but I’m not the mechanic. Smoke like hell and sound like it too but always leveled out after 5 mins or so…miss abusing that beast..

    1. Hi Denny,

      I’ve run into this issue with my snowblower. Gas doesn’t vaporize and combust as readily in cold temperatures, so it often helps to warm the carburetor with a space heater. That’s what I did with my snowblower. Just be careful to place the heater close enough to heat the carb, but not so close that you start a fire. And don’t leave the heater unattended. It shouldn’t take more than a few minutes.

      Good luck, and thanks for reading.

  4. I discovered MP for a starting fluid long ago, and recommended it many times because it is a lubricant VS ether that does wash away residual oil film on cylinder walls

  5. Good article, I haven’t used starting fluid in a long time . The reason is because of something I discovered while working on a old dirt bike motor. It was a 2 stroke and I was having trouble getting it to start . Since I didn’t want to use starting fluid because it is so hard on the cylinder I decided to try a spray lube. Turns out Amsoil MP makes a great starting fluid. I have used it hundreds of times on both 2 and 4 stroke motors and it works every time and also is easier on the cylinder because it is a lubricant. Just shoot some in the carb , air box or cylinder and it will fire right up.Feel free to send me some as I am running low, LOL.

    1. Hi Eric,

      I’ve used MP for a lot of jobs, but starting an engine hasn’t yet been one of them. Thanks for the story. I’m sure some of the people around here would cringe at the thought of using MP as a starting fluid, so don’t look for us to update the recommended uses any time soon!

      Thanks for reading,


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