Here's What Can Happen When You Use Starting Fluid In A Diesel Engine

What are your thoughts on your car's diesel engine? Do you like it? Would you like it to stay in one piece and not explode? If the answer is yes, then you'd better listen up, because there's something you should almost never put in your diesel motor if you want to keep it in good working order and not have it be all explode-y. With just one exception, starting fluids — including ether — should never be used in a diesel engine because, well, there's a really high risk of detonation, as Diesel Hub puts it.

Starting fluids are volatile, highly flammable compounds that are typically packaged in an aerosol spray that can be applied to a car's air filter or intake in order to help get it started by aiding in combustion. Typically, they're meant for gas motors, and despite what the labels might say, they are not really safe for use on diesel engines. That all has to do with how diesel engines operate versus gas engines. I won't get into how a diesel engine works versus a gas motor, but all you need to know is that, by way of design, a diesel engine has no way to control the combustion of any fuel being compressed with its air charge. As soon as the mixture reaches its flash point, it will ignite spontaneously.

That's where the starting fluid issues come into play. Because diethyl ether has a lower flash point than that of diesel, it's easier to ignite, so the entire air-fuel mixture could end up igniting before the completion of the piston's compression stroke. When that happens, the piston and the rest of the gear train will absorb the pre-combustion event, which is also known as detonation. It's really bad news when that happens. We're talking catastrophic engine failures — broken pistons, wrist pins, connecting rods, cracked engine blocks and blown head gaskets, according to Diesel Hub. If you can dream of it breaking. It can happen.

As with all rules, this one is meant to be broken, as well, but you've got to be very careful. Diesel Hub says starting fluid can be used on some diesel engines, but only when the manufacturer explicitly states that it's safe to use. Usually, that's only on engines that are 20-plus-years-old, do not use glow plugs to help with start-up and have relatively low compression ratios.

Think of old diesel cars and trucks — old farm equipment too — the sort of stuff that might as well be running on vegetable oil. Those are the types of vehicles that could probably be alright if you used starter fluid on them, but anything newer than that, and you're heading for detonation city. That's not where you want to be, is it? I didn't think so.

I'm sure I'll get some comments from people talking about how they use starting fluid on their modern diesel motors when it's really cold out, but they're either reckless or lying on the internet, which is something nobody should ever do.