Finding an oil leak on your garage floor is irritating. Not to mention stressful, most folks rely on their truck for their livelihood. But better to find it and fix it before it develops into a serious problem. I’m a mechanic, and together we’ll get to the bottom of this.
The most common cause of an F150 oil leak after an oil change is because of an oil splash trapped on the skid plate.
In this post, you’ll learn the most likely reason your F150 leaks oil after an oil change, how to diagnose it, and fix it quickly.
Common Cause of F150 Oil Leak
The most common reason your F150 leaks oil after an oil change is that the mechanic simply failed to clean up the oil splash thoroughly.
When changing F150 engine oil, oil splash during the draining process with some engine types just can’t be helped, especially if it’s a fast lube type service. That said, a good operator will thoroughly clean up the oil splash and double-check their work before calling it good.
When changing the F150 oil, oil draining onto the anti-roll bar and skid plate is likely; inexperienced fast lube operators spilling fresh oil down the side of the engine is common too.
A pro shop will use an oil-filling machine that saves time and the risk of spilling, but the smaller shops rely on a steady hand and a plastic container which often could be more steady. And guess where all the spilled fresh oil goes? Correct! It takes some time, maybe a day, to eventually drip from the skid plate.
Next, we’ll look at how you can quickly check if that is indeed the issue.
Oil Leak Diagnosis
As soon as you become aware of an oil leak, it’s best to attempt to locate its cause before driving it. Or, at the very least, ensure the leak isn’t a major one.
First, go ahead and check the oil level. A low level means you may have a serious leak, and it is best not to run the engine or drive the truck until we locate its source.
Finding your oil level is ok is great news, it means we can still drive the truck, but we’ll still need to attempt to locate the source.
Using a flashlight or the light on your phone, try and locate the source of the leak from the underside of the vehicle.
Oil around the skid plate is a telltale sign we are dealing with a sloppy cleanup after your oil change. But we’ll need to pop the hood and see if we can see any oil splash top side.
Oil top side isn’t expected. As said, we expect it’s a case of a poor cleanup. If all looks good topside, you have two options, take it back to the dealer or pull the skid plate and do the cleanup yourself.
If you decide to do it yourself, you’ll need a can of brake cleaner; you’ll need to pull the skid plate and wear eye protection spray down the splashed oil from the oil pan and the skid plate.
Ensure your oil filter and oil bung areas are clean before idling the truck for ten minutes to double-check for any further leaks.
All looks good to replace your skid plate and call her good.
Other Possible Causes Of F150 Oil Leak
While an oil splash caused by the draining process is the most likely root cause of an oil leak after an oil change, it isn’t the only cause. Here’s a list of some other common causes, the diagnosis, and the fix:
Loose oil drain bung
Obviously, a loose oil drain will leak. You’d expect a pro-oil change service to get the basics right, but obviously, it happens.
Diagnosis – Clean around the oil drain and run the engine to check for a fresh drip.
Fix – Loosen the drain bung and retighten to spec.
Cross threaded bung
Cross threading of the oil drain happens when the oil drain bung is incorrectly threaded into the oil pan and when tightened, it cuts through the threads of the oil pan, damaging them permanently.
There are a few reasons this happens as often as it does. Firstly oil pans are often alloy which is a soft metal and easily damaged.
Secondly, air tools are used to remove and fit fasteners which is a ton faster than wrenching but doesn’t offer the user the same feel for what’s happening at the threads.
Thirdly, oil changes don’t bring in a ton of revenue for workshops, and the technicians are under constant time pressures to execute the job more efficiently. (Not an excuse for shabby work, just an observation)
Diagnosis – Clean the oil drain area thoroughly with brake cleaner and a rag, run the engine, and confirm a leak. Go ahead and unthread the bung using a wrench to access the thread feel. A damaged cross-threaded bung will bind and require excessive force to remove.
The Fix – The threads on the oil pan will either need to be cleaned up if not too badly damaged, or they’ll need to be tapped and a new larger bore oil drain used. It is possible to use pipe dope to prevent the bung threads from dripping oil, but this is a temporary fix and will cause endless issues after every oil change.
Worn bung washer
Oil drain bungs employ a seal to prevent the bung from leaking. The seal usually comes in the form of a washer or rubber O-ring. The seal should be replaced whenever it’s opened; many seals are one-time use only.
Diagnosis – Ask the fitter if they replaced the seal.
The Fix – Replace the seal.
Over-tightened oil drain bung
Over-tightening is common. Oil drain bungs need to be tight, but not lug nut tight. The torque spec varies by engine, but somewhere about 10 ft. lb. is normal.
Diagnosis – Loosen the bung, retighten and check for further leaks.
The Fix – You won’t need a torque wrench to tighten an oil drain; after the drain bung seats, tighten a further, usually another ¼ turn approx.
Oil filter leaks
Oil filters come in two flavors, screw-on metal or cartridge. Both can leak if not fitted correctly.
Metal type – The metal screw-on type is frequently overtightened, which can cause the seal to pinch and leak. Leaving the old rubber seal on the oil filter housing accidentally is another somewhat common error, the double seal leaks as oil pressure builds. Fitting the oil filter without first oiling the rubber seal can sometimes cause a leak.
Cartridge type – The cartridge type can be challenging to fit; the rubber can be located O-ring seal can be fiddly to remove and refit and is sometimes skipped by the mechanic. Reusing the old seal obviously increases the risk of a leak.
As with the metal screw-on filter, the cartridge O-ring seal should be oiled and the cap tightened to spec; the spec is embossed right into the cartilage plastic cap.
As with the oil bung, a torque wrench isn’t required; after the filter seats,
F150 employs a useful oil filter splash guards, and they need cleaning – F150 filter drains, if not cleaned thoroughly, are a source of oil drips. The 5.0l has two oil drains which you can check out in the video below.
Sum Up
A messy oil change technician is the most common cause of an F150 oil leak after an oil change. A quick inspection and a visit to the dealer for clean-up is the usual fix. Make sure you get credit for your next oil change but check for leaks before you leave.