In theory, your oil filter has a simple job: capture wear-causing contaminants and hold them in the filter media so they don’t run amok throughout your engine.
But lots of factors can throw a wrench into this plan, which can raise questions about oil filters and filtration. Here are some of the most common.
The oil filter is designed to capture contaminants and hold them within the filter media. Over time, the media fills with dirt particles, agglomerated soot, metal particles and other junk. If the filter plugs, the pressure differential will open the bypass valve, which allows oil to bypass the filter, preventing oil starvation. Sure, dirty oil is preferable to no oil, but it’s not a long-term plan you can trust. When an oil filter bypasses, no filtration occurs; it only passes oil through (bypasses the filter media) to provide the required oil flow for the engine.
A new oil filter is far less expensive than a new engine. Don’t cheap-out – replace the filter with every oil change.
It depends on filter quality and your driving conditions.
A low-quality, cheap conventional filter doesn’t offer the capacity of a filter using synthetic media, meaning it fills with contaminants faster and requires more frequent changes. Plus, if you drive in dusty, dirty conditions, your engine is exposed to increased levels of airborne dirt particles that can enter the engine, especially if you haven’t changed the air filter in awhile or there’s a leak in the intake system.
Some modern direct-fuel-injection vehicles experience elevated fuel dilution, which also takes a toll on the oil filtration system. In diesel engines, soot particles can agglomerate into larger contaminants and lodge in the filter. This all adds up to more contaminants and more stress on the filter.
Follow the filter manufacturer’s service guidelines. If none are given, go with what’s recommended in your vehicle owner’s manual.
No. Just change the filter as normal. After the new filter is installed, run the engine for a couple minutes, then shut it off and allow several minutes for the oil to settle in the sump. Check the oil level and top-off as needed to make-up for the oil removed with the old filter. Remember, the oil is in the oil pan. It won’t run out of the filter housing or mount.
The Internet is full of pre-fillers and anti-pre-fillers, all of whom seem able to reference a high-mileage conversion van or pickup they’ve serviced for decades either pre-filling or never pre-filling the filter.
Some filter manufacturers say pre-filling the filter isn’t necessary. But remember – they make filters, not engines. There’s a reason engine manufacturers recommend 0W-XX or 5W-XX motor oils, and it’s so the oil flows readily at startup when it’s cold and the engine doesn’t go without vital lubrication while it builds oil pressure.
To help ensure the engine doesn’t start dry, we recommend you pre-fill the oil filter if you can. Horizontally oriented filters can pose a problem, but even they can be pre-filled with some oil. I typically pour a little oil into the filter and tip it sideways and check the oil inside. If there’s room for more before it begins to spill out of the opening in the filter, I add a little more oil before installing the filter.
Use a filter made with synthetic media for best protection. Synthetic oil filters offer the following benefits:
Most spin-on oil filters contain the following:
Here is a view of the components in an AMSOIL Ea® oil filter:
Yes, it’s perfectly safe to use either type of filter with either type of oil. However, if you practice extended drain intervals using synthetic oil, a conventional oil filter may not offer the required service life, meaning you’ll have to change it in the middle of the oil drain interval, which is inconvenient. That’s why AMSOIL Ea Oil Filters are constructed to last 25,000 miles between changes, coinciding with the 25,000-mile drain interval of Signature Series Synthetic Motor Oil. AMSOIL Ea15K Oil Filters offer 15,000-mile change intervals. The reason for the difference is the size, which affects capacity, not efficiency. Many newer cars and light trucks are designed to use smaller oil filters which have a smaller filter media, thus a shorter service life because of less capacity.