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."