This seemingly insignificant part could cost you thousands if you choose the wrong one. We try to make sense out of the choices.      

I like to think of myself as an expert on engines, at least in comparison with the general public. But when I stare at the wall of oil filters at the Wal-Mart, I’ve always felt somewhat helpless. There are too many choices, they all look the same on the outside, and there’s a big difference in price. The temptation to “cheap out” is strong, and on occasion, I’ve done just that. The bottom line is that the lowly oil filter traps particles that accumulate in bearing material and other critical areas of your engine. By catching the debris before it takes its toll, you’ve extended the useable life between rebuilds, which can get expensive in our world of big-dog street cars.

Today, we had a very interesting meeting with the folks at Fram. Specifically, I got to talk with Gary Bilski, the chief engineer at Fram. I asked him a lot of pointed questions about Fram’s test procedures, their filtration materials, filter construction, and application recommendations for high-horsepower street engines, and boy, am I glad I did.

As the cut-away filters were passed around the table and I got to look inside, the differences between the Fram Extra Guard, Tough Guard, Xtended Guard, and High Mileage filters became clear after some extended questioning. In a nutshell, here’s the diff:

Extra Guard: This is the basic Fram orange filter I’ve been using for years. It’s got the SureGRIP bottom for easy install and removal, and has market-leading filtration at 96 percent single-pass efficiency. This number means 96 percent of dirt particles 20 microns and larger are filtered out in one pass. The last time Consumer Reports tested oil filters, this one was the best out of all of them, which is why I’ve been using it all these years.

Tough Guard: This one’s worth a close look for high-performance street engines because it has a combination of cellulose and synthetic glass filtration fibers. This filter media filters out much smaller particles, and does it over a longer period of time (i.e. it holds more dirt before choking up and putting the oil system in bypass mode). The thing that raised my eyebrows is the screen-over bypass valve, which filters out larger particles regardless of whether the filter is in bypass or not. If hell breaks out in your solid-roller street engine, this is going to catch chunks and save hardware. Fram says Tough Guard offers six times the duration protection of your typical low-buck generic filter.

Xtended Guard: This is the new sheriff in town, and features an even higher percentage of synthetic glass fiber in the filter blend than Tough Guard. This means even more dirt carrying capacity (about 70 percent more dirt can be collected while maintaining filtration), and being able to filter out a lot more smaller particles. Both the Xtended Guard and Tough Guard feature anti-drainback technology to keep oil in the top end of the engine when it’s shut down. The one caveat is that OEM filters that didn’t have this feature don’t get it in the Fram line either. Example: the ever popular TG30 and XG30 for small- and big-block Chevy don’t have this, so buy the late-model TG5 and XG5, which is the same, only longer in the body. Fram says Xtended Guard is good for 10,000 miles, which helps me a lot, since I use synthetic oil, which has a longer drain interval. With the filter now up to snuff with the synthetic oil life expectancy, I can breathe easy.

High Mileage: This filter is designed specifically for engines with a lot of miles on them. Let me rewind for a second. The Holy Grail of engine oil manufacturers is to keep the additive package in force for long intervals, especially on older engines over 75,000 miles. The reason is that these engines need more protection to make up for engine wear and looser clearances. Except that oil additives become depleted before the oil’s base stock is out of steam. The Fram High Mileage filter actually packages a time-released additive package that gradually dissolves over its life expectancy, so feel free to use your more expensive synthic on your older performance engine in conjunction with the Fram High Mileage.

So what do I plan on using? I’ll be checking out the Tough Guard and the Xtended Guard. The Tough Guard is not that much more expensive that the Extra Guard (Summit sells the Extra Guard for $5.95, and the Tough Guard for $8.95). I like the screened-over bypass valve and the synthetic glass fiber filtration for the 496 big-block Chevelle and the new 408-ci small-block in the Laguna project. Both take the same TG5 part number. The Xtended Guard with it's superior filtration and long life sounds like my pick for a daily driven performer, like my '03 Mustang, so I'll be giving that a try next oil change too.