Get Proper Insurance For Your Oil

by Curt Bennink
Created: October 1, 2005

Matching filters to the application and proper installation are crucial to oil system performance.

But there are also downsides to pre-filling filters. Elfers explains, "Your first thought would be that pre-filling prevents oil starvation during engine startup, and therefore should be standard operating practice. This has limited value, however, as oil changes should be done on warm engines and these will have a fresh coating of oil on all vital parts. The momentary starvation of oil on startup is negligible compared to the potential harm that can result from introducing contaminants in the pre-filling process."

If you do choose to pre-fill the filters, make sure to take adequate precautions. "It is important to recognize that contamination removed from the engine lube system by the full-flow filter is, for the most part, smaller particles than the eye can detect," says Birch. "You cannot take too many precautions regarding the cleanliness during oil changes and engine service."

Don't just randomly pour oil into the filter. "If you do pre-fill, pour the oil in the dirty side, where all of the smaller holes are, so you are getting the oil to go through the filter," says Hacker. "That way, any contamination in the oil will have to pass through the filter. That is kind of an inconvenience for some people, but it is what we recommend."

"When filters are pre-filled through the threaded hole in the baseplate, the oil is going directly to the clean side of the filter. It will not be filtered prior to its path through the pressurized lube system," Birch points out.

"Trying to add oil only to [the outside holes] of the filter is a good intention, but difficult in practice," says Elfers. "The safer practice is not to pre-fill."

Don't Get Scammed

When comparison shopping, it's easy to be confused by advertised micron ratings published by various filter manufacturers. A micron (a millionth of a meter) is simply a metric unit used to measure length, width or diameter. The micron rating indicates a filter's ability to remove particles of a given size. But when a manufacturer claims to have a 15- or a 10-micron filter, this alone doesn't really tell you much. What you really need to know is how efficient the filter is at removing certain micron-size particles.

Suppose a supplier claims to have a 10-micron filter that it will sell you at a lower cost than you are paying for your current 15-micron filter. To get the whole story, you need to compare published efficiency ratings at a given micron size. It may be that your current 15-micron filter is 40% efficient at removing 10-micron particles, while the supplier's 10-micron filter has an efficiency rating of only 35%.

"If you are comparison shopping on data, make sure your data is for the same specification. For example, you want to say, 'I have a 90% efficiency filter at 5 microns per ISO 4572,' " says Keith Bechtum at Donaldson. "You really want to make sure you have the specifications on which the test data was run. That is really the only way you can do it. You will see a lot of information out there with very old test specs."

Higher efficiencies generally translate into cleaner oil. "Filters with higher particle removal efficiencies can reduce the concentration of contaminants, and in sizes smaller than a filter with a lesser rating can achieve," says Brent Birch, Champion Laboratories, supplier of Luber-finer filters. "Sometimes this advantage is significant and other times the stated performance difference is in the noise range of the test procedure. For those cases, the performance advantage can only be detected by a specialized testing laboratory."

"Efficiency and capacity are the obvious comparison factors, but these are just the starting points," says Bert Elfers, Baldwin Filters. "How can you be sure you are getting filters without internal leaks, poor workmanship and other overly cost-reduced components? The answer is to select a brand that you can trust. That way, you know that professionals using detailed evaluation and testing have already made the 'apples to apples' comparison and are standing behind their recommendation."