Quote:
Originally Posted by cfg83
1 - What do you think of using a larger oil filter for MPG?
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It might help some, but it's my understanding that it isn't size per se that matters.
What really matters (in a filter) is a combination of the filter's ability to filter, along with its ability to let the oil easily flow. Better oil flow rate can help FE, because it can lower parasitic losses on the engine. Likewise, cleaner oil is better for FE than "dirty oil", and the better the filtering ability (of the filter) the cleaner your oil will be.
Now it is true that all else being equal, a bigger filter should flow a little easier (more surface area for the oil to flow through), and also filter a little better (due to more filter media being in the can). So all else being equal, a bigger filter (that physically fits in the application) should be a little better.
But the thing is, frequently all else is NOT equal, as filters vary a huge amount in both the quality of their construction and the ability of their filter media to filter. So a quality smaller filter will win out over a bigger (less well constructed) filter almost every time!
NOTE:
Last I heard (and also what I use), the Amsoil EAO filters (and their fully synthetic filter media) are just about the best filters on the market these days, for their combination of filtering ability (both how fine of filtration they do, how much junk you can remove before they fill up) and their flow rate (which is amazingly good, especially in such a fine filter). And I'm not just saying that because I have an Amsoil dealership, but rather because I not only use that filter myself (and seen what it can do), I've also seen its filtering specs, as well as seen the results of independent tests done by some people over on the "Bob is the Oil Guy" forums.
NOTE:
If you really want the ultimate in filtering, combine a really good full flow filter (such as the already mentioned EAO filter), with what is know as a "bypass filter". A bypass filter, is a 2nd (doesn't replace the main) filter that is plumbed into your car, so that a small amount of oil is SLOWLY filtered very well (often down to 2 microns filtration, or even finer). The idea is, that very fine filtration often affects flow rate, and therefore it's hard to get both good flow (needed for the engine to get enough oil) and good filtration (needed to clean the oil of fine partials) in the same engine filter. Although some filters (the EAO probably being about the best on the market), make a good faith effort (by using better technology and better quality manufacturing) to do both with main engine filters, in the end you always have a trade-off between fine filtration and oil flow rate. So what a bypass filter does, is not worry about the flow rate issue, as it's designed to NOT be the primary filter in front of the engine, but rather to just supplement the main filtration by slowly doing a very good job of filtering/cleaning the oil in the crank-case. This results in TWO oil paths in the cars, the main (full flow) path as before, and a 2nd path that doesn't even try to meet the engine's oil flow needs, but instead just works to ultra-clean the oil.
And FWIW: Yes my CRX does use both a bypass filter and an EAO full flow filter, for just about the ultimate in keeping my oil clean and flowing. This, combined with the high quality synthetic oil I use, not only seems to help my FE, but also means that I can easily go 10 to 20 thousand miles between oil changes (because the synthetic oil breaks down so slowly, and the filter combination keeps the oil ultra clean)!