The oil filter plays an irreplaceable role in the lubrication system of construction machinery: Though seemingly insignificant, the small oil filter occupies an indispensable position in construction equipment. Just as the human body cannot function without healthy blood, machinery cannot operate effectively without proper lubrication. Once the human body loses too much blood or its blood composition undergoes a significant change, life itself is seriously threatened. The same holds true for machines—without the oil filter to remove impurities, engine oil would enter the lubrication system directly, carrying debris into the metal friction surfaces and accelerating component wear, thereby shortening the engine’s service life. Although replacing the oil filter is a remarkably simple task, using the correct procedure can significantly extend the machine’s lifespan.

　　1. A good-quality air filter is bound to look attractive.

　　Oil filters from well-known brands not only use high-quality materials and feature superb craftsmanship, but also pay meticulous attention to even the smallest aesthetic details—only established brands are willing to invest in perfecting these details. Counterfeit or refurbished oil filters simply don’t have the capability, nor do they bother to get them right.

　　The approach of “judging a filter by its appearance” is actually quite effective, because a good-quality filter will inevitably have a good-looking exterior. As for cheap filters, their very origin is highly suspect—these filters may well be refurbished used ones, reassembled after being given a facelift and then resold. Naturally, any process that can be cut corners on will be.

　　2. Check whether the rubber ring of the oil filter is resilient and soft.

　　The rubber ring at the oil inlet and outlet of the engine filter is also one of the indicators for judging whether the filter is good or not. You can remove the rubber ring and pinch it gently with your fingers to feel its texture.

　　A good oil filter will have a thick, robust rubber seal, and when squeezed by hand, it will feel soft and flexible—ensuring a tight seal around the oil inlet and outlet ports.

　　3. Check whether it has a check valve structure inside.

　　Whether or not a fuel filter is equipped with a check valve is also an important criterion for assessing its quality level. You can use a small tool handy around you to determine whether a fuel filter has a check-valve structure.

　　The oil filter check valve is actually just a rubber cup—a very simple component, yet its role is remarkably important. It prevents oil from flowing backward, ensuring that as soon as the engine starts cold, oil pressure can quickly build up within the lubrication system, thereby guaranteeing adequate oil supply and minimizing the duration of dry friction during engine startup.