You likely already know that your car needs an oil change every 3,000 miles or so, but what do you do when the oil light comes on shortly after that oil change? If you're not really familiar with the mechanics of your car, you may not know where to start to make sense of it. The good news is that there are only a couple of things that are typically to blame for this. Understanding the most common causes will help you narrow down the issue before you have to take your car back to the garage.

No Oil

Sometimes even the best oil change technician can forget to fill the oil pan during an oil change. Since all of the oil is drained out in the beginning of the process, this can leave the engine starved for oil. If the oil light comes on almost immediately after you leave the garage, this may be the likely culprit. Check the oil level on the dipstick. If it doesn't register, that's what's to blame.

Loose or Missing Drain Plug

The oil pan is fitted with a drain plug to allow you to drain the oil out before it's replaced with fresh oil. Once the oil pan is drained, the plug is screwed back into place to seal the pan so that the oil that's added afterward stays in the engine. If, however, the drain plug isn't completely tightened or is omitted, you'll lose oil. When the oil light comes on right after you leave, that may be due to a missing drain plug, but if it comes on a little while later, it may be that the drain plug is loose and oil is seeping by the seal. You can check the drain plug by crawling under the car. The oil pan is usually directly beneath the engine or just behind it.

Loose Oil Filter

The oil filter sits on the engine and cleans the oil as it circulates. It has a gasket on the top of the filter, and that gasket helps to form a seal that keeps you from losing oil as it passes through the filter. There are several possible reasons why you might be losing oil past the filter. If the technician didn't get it tight enough, it will lead to leaks. You might also lose oil past the gasket if the gasket wasn't brushed with clean oil before the filter was inserted. The clean oil  helps it seal tightly. You might also lose oil past the filter if it was not installed straight. If the filter is slightly off-center in the mount, it won't seal tightly, so it will allow oil to leak.

The Wrong Weight Of Oil

Your car's engine is rated for a specific oil weight. That weight is what performs best in the engine. If you change the engine oil and replace the existing oil with one that's a heavier weight than your car's engine is rated for, that can lead to an oil leak. The heavier weight of the new oil could actually cause a pressure buildup in the oil lines, causing seals to blow because they aren't rated to withstand that pressure. When the seals blow, your engine will lose oil, causing the oil light to come on. This may take a little time, though, so the light wouldn't come on for a short time after the oil change is done.

The Detergents In The New Oil May Flush Debris From a Leak

If it's been a little while since your last oil change, you may have contaminants and debris from the old oil that have settled into cracks that would otherwise be leaking oil. When the fresh oil hits the system, the detergent additives in new oil that are designed to eliminate sludge buildup in your engine will flush those particles away. This can clear out that crevice and allow oil to seep through, leaking from your engine. This is usually a slow leak, though, so it will take time before the oil level gets low enough for the oil light to come on.

To learn more about oil changes, contact a company like PDR Automotive Inc.