Using an ls oil priming kit is the best way to make sure your freshly built engine doesn't destroy itself within the first ten seconds of turning the key. If you've spent any time in the garage working on a Chevy project, you know that the LS platform is legendary for its power and reliability, but it has one specific quirk that can give even seasoned mechanics a bit of anxiety: the oiling system. Unlike the old-school small-block Chevys where you could just pull the distributor and spin the oil pump with a drill, the LS pump is mounted directly to the crankshaft. That design change means you can't just "spin it up" to get pressure before the first fire.
That's where the priming kit comes in. It's essentially a pressurized tank that forces oil into the engine's internal galleries before the crank even moves. Think of it as a preemptive strike against metal-on-metal contact.
The Stress of the Dry Start
We've all seen it—or worse, heard it. You spend months gathering parts, nights scrubbing grease off the block, and thousands of dollars on a rotating assembly, only to have the engine "clack" for five long seconds during the first start because the bearings are bone dry. That sound is the sound of your investment literally shaving years off its life.
In a perfect world, assembly lube would handle everything. And sure, good assembly lube is vital. But it's not meant to take the place of actual oil pressure. The LS engine oiling path is a bit of a journey. The pump has to pull oil from the pan, push it through the filter, up into the lifter galleries, and finally out to the cam and main bearings. If you're just relying on the starter motor to turn the engine over and build that pressure, you're asking those bearings to survive on a prayer until the pump finally catches its prime. An ls oil priming kit removes that variable entirely.
Why the Old Drill Trick Doesn't Work
If you grew up working on 350 or 454 engines, you're probably used to the "distributor hole" method. You'd get a long hex tool, stick it down into the block, hook it to a heavy-duty drill, and spin it until the pressure gauge on the dash jumped up. It was easy, effective, and gave you a warm fuzzy feeling before you dropped the cap back on.
The LS changed the game. Because the oil pump is driven by the crank snout, it only spins when the engine spins. You can't get to it with a drill. Some guys try to prime them by removing the spark plugs and cranking the engine over with the starter for a minute or two. While that's better than nothing, it's still not ideal. You're still putting load on the bearings, and you're still moving parts without a pressurized film of oil protecting them. Plus, starters aren't exactly designed for long-duration duty cycles like that.
How the Priming Kit Actually Functions
A proper ls oil priming kit is a pretty simple piece of hardware, but it's incredibly effective. It usually consists of a canister that holds a few quarts of oil, a high-pressure hose, and an adapter that fits into the oiling system. Most people use the oil pressure sensor port at the back of the block or the oil gallery plug on the front driver's side of the engine.
You fill the canister with your choice of break-in oil, hook it up to an air compressor to pressurize the tank, and then open the valve. You'll literally watch the oil disappear into the engine. Because the system is under pressure, it forces that oil into every nook and cranny. It fills the lifters, coats the cam lobes, and ensures the main and rod bearings are completely submerged.
The coolest part? You can actually watch your mechanical or digital oil pressure gauge climb while the engine is sitting dead still. When you see 30 or 40 PSI on the dash without the crank even turning, you know you're ready to go. It takes all the guesswork out of the equation.
Choosing the Right Port for Priming
When you're setting up your ls oil priming kit, you have a couple of options for where to "inject" the oil. The most common spot is the oil gallery plug on the front left side of the block, near the alternator. It's an M16x1.5 thread, and most decent kits come with the correct adapter for it. This is arguably the best spot because it's at the beginning of the oiling circuit, meaning the oil has to travel through the entire engine to get everywhere else.
Another option is the oil pressure sensor port at the back of the intake manifold. This works too, but it's a bit more of a pain to get to if the engine is already in the car. If you're priming the engine on a stand, it doesn't really matter which one you use, but the side gallery plug is usually the path of least resistance.
DIY vs. Buying a Professional Kit
If you're a hardcore DIYer, you might be tempted to build your own ls oil priming kit using a garden sprayer or an old fire extinguisher. People do it all the time, and there are plenty of forum threads showing you how. If you're on a super tight budget, it beats skipping the process entirely.
However, there's something to be said for a dedicated kit. Professional kits are built to handle the pressure without leaking oil all over your clean garage floor, and they come with the specific metric adapters you need for the LS block. When you've spent five grand on a forged bottom end, spending a little extra on a tool that works perfectly every time is usually a smart move. Plus, once you have it, you'll find yourself using it for every project—or lending it to friends who are finally joining the LS swap club.
The Peace of Mind Factor
There is an emotional component to this, too. Building an engine is stressful. There are a thousand tiny things that could go wrong—a missed torque spec, a backwards ring, a piece of lint in an oil passage. When the time comes to finally twist the key, your heart is usually racing.
Having used an ls oil priming kit, you've at least eliminated one of the biggest risks. You know for a fact that the bearings aren't dry. You know the oil pump is primed and ready to take over the second the engine fires. It turns that first-start moment from a "please don't blow up" prayer into a "let's hear this thing roar" celebration.
A Few Pro-Tips for the Process
When you're using your kit, don't just dump a gallon of oil in and walk away. I like to rotate the engine by hand with a breaker bar on the crank bolt while the system is under pressure. This ensures that the oil holes in the crank line up with the holes in the bearings at different intervals, making sure every surface gets a thorough soaking. It only takes an extra minute, but it's the "extra mile" that ensures a perfect break-in.
Also, make sure you're using a high-quality break-in oil with plenty of ZDDP (zinc and phosphorus). Even though LS engines use roller cams—which are much less sensitive than flat-tappet cams—the high pressure and friction of a new build still benefit from that extra protection. Once you've pushed a few quarts through the priming kit, you can top off the oil pan to the proper level and you're good to go.
Final Thoughts on Engine Longevity
At the end of the day, an ls oil priming kit is cheap insurance. Whether you're putting together a junkyard 5.3 for a turbo project or a high-dollar 427 for a track car, the physics remain the same. Metal moving against metal without lubrication is bad news.
It's easy to get impatient when you're at the finish line of a build. You want to hear that exhaust note. You want to see if the tune is right. But taking that extra thirty minutes to properly prime the system is what separates a build that lasts 100,000 miles from one that ends up back on the stand two weeks later. If you care about your LS, don't skip the prime. Your bearings will thank you, and your wallet will too.