By-pass filters pros and cons

As a practical matter, I'd probably not recommend a bypass for your application.
Just use a good synthetic. A bypass filter makes a lot of sense for diesels, for fleet use, for vehicles or equipment run lots of miles/hours per year.

Good Point Dick. Also justifying the price is easier in diesel applicatons because of higher crank case capacities.

David

In general, I think VERY few people drive enough miles on a car/light truck to see a financial benifit from a bypass filter. 10k/year isn't anywhere near high enough! Having said that, although I like Rotella 5W40, I might consider Delvac 1 (avalible as Mobil 1 5W40) in this application if I wanted to extend drains out beyond 10k.

I thought the reason for using a bypass filter was that it had a smaller particle screening size, and so reduces wear. The lower wear is an advantage no matter what number of miles per year are driven, right?

http://vs01.tvsecure.com/cgi-bin/vs01037/faq/smartfaq.cgi

My point was that there is no financial benfit from running a bypass filter for the vast majority of the driving public. How many people do you know that have had an oil related failure under 150,000 miles in the last 10 years? Specifically a failure caused by wear, not sludging or similar. Personally, I don't know of any that weren't manufacturing/design defects=warantee issues.

If you drive enough miles to wear out the engine before the rest of the car, then the bypass filter makes since. And given that even the crappiest SL rated dino and cheapo filters will get you to between 150,000 and 250,000, it is hard to make an argument for the bypass filters unless you drive 30,000+ miles a year.


Of course, if you simply have a strong desire to have a bypass filter, as long as the placement is done correctly in the oil circuit, there isn't a substantial reason not to have one. Espicially if your car is already out of warantee.

Dear 73Duster:
I am a filtration consultant. By-pass filters are used to improve filtration performance, keep the oil cooler and increase drain intervals.

For your application, I would not recommend a by-pass filter. You do not drive enough miles in a year. Secondly, the main concern in your region of the country is condensation in your oil.

Thus, changing your oil is still the best course of action.

You should also consider other beneficial factors like -improved fuel milage -reduced wear on engine better emission control and so on.
Also remember that an investment in an additional filter system should be considered from an life-cycle piont of view or at least the time you are responsible for the maschine/vehicle.
This means that longer oil change intervals are just a small part of the big picture.
For example will reduced fuel consumption mean 5-15 %savings on fuel expense.
Also remember that we all benefit from a cleaner environment.
I recently mounted a by-pass filter on an old Chevy 350 cid V8(no computer-controlled engine)
After a few hours driving idle speed increased from 800 to more trhan 1000 RPM.
This is a very good and simple prove that internal friction is reduced and the machine needs less fuel.

Increased fuel mileage from a bypass filter? With a 5-15% claim...uh, I really want to see tests on that.

Neither gulf Coast Filters, Motor Guard, or Frantz makes a fuel economy claim. I don't think Amsoil does either. Can anyone point me to a bypass filter company that does?


I cannot think of a logical reason why a bypass filter would reduce friction compared to new oil...that is, if the filter is removing very fine friction causing particles from the oil, the same mileage increase should happen everytime one changes their oil, right? So if you actually saw a fuel economy gain, you should be able to replicate it with frequent oil changes. Same for the idle speed business.


I've owned gas engines with bypass filters...none of them showed anything remotely resembling a fuel consuption decrease. Some engines respond to a different viscosity of oil, or a switch to synthetic in a small mileage increase...but to a bypass filter?

Take a look at:

Jim Fitch, "Clean Oil Reduces Engine Fuel Consumption". Practicing Oil Analysis Magazine. November 2002



http://www.practicingoilanalysis.com/article_detail.asp?articleid=401&relatedbookgroup=PowerGen

Best regards

Obviously, I'll have to dig through some SAE papers to read the actual studies, but initial impressions are as follows:

Every study mentioned in that practicing oil analysis article involves diesel engines. A bypass filter is particularly useful on a diesel do to the soot contamination problems (and radically longer drain intervals). The article(s) also give little detail about the oil types used and the oil change intervals.

A drop in wear metal numbers due to a bypass filter does not necessarilly have any connection to reduced wear, in that one would hope that the bypass filter would be trapping particle that would otherwise show up as insolubles and wear metals on a analysis report. Therefore, in the absence of actually measurements, I find the 93% Iron generation claim misleading. I do think that bypass filters allow longer drain intervals, and slightly decrease wear, but you would never pay for one based on that line of logic unless you drive a great deal per year.

It is well established via SAE papers (2003-01-3119) that wear metal generation in PPM/1000 miles actually decreases as oil ages in an engine, up to a certain point. I have trouble rationalizing this phenomena, which I've seen first hand, with a massive wear reduction from a bypass filter ON GAS ENGINES WITH REASONABLE DRAIN INTERVALS.


I've yet to find a bypass filter manufacturer, for gasoline passenger cars that claims a fuel economy improvement. If noone else, I would expect Amsoil to claim it, if they thought they had a fighting chance agains the FTC. Also, to go further, a gain of, say 3-5% would be well worth it for CAFE reasons given the relatively insignificant cost for a car maker to simply install a Bypass filter from the factory. (If for example, GM could pick up 5% in fuel savings across theirline, they would jump at
it.


Finally, modern fuel injected engines seem to maintain fuel economy out until at least 150,000 miles on regular dino changes. As a quick example, I recently worked on a friend's 1992 Mazda Protege, which despite a diet of 4,000 mile changes on cheap dino still has factory spec compression, and unchanged mileage at 225,000 miles.

One thing to keep in mind, the AMSOIL bypass filters also remove water from the oil. The water from condensation can be a problem in your area, especially on vehicles which only get low miles.

Something to think about!

Sort of a catch-22 though isn't it? I mean the cars that see low oil temps and low useage are the worst about actually see a cost per mile benifit from the filter.

There is an extermely gimmicky bypass filter on the market that contains an electric heating coil to boil out water...I've always thought that people would do better to just get their oil temps up once in a while! (That particular product has a number of other problems as well) As a side note, since I seem to rip on Amsoil a lot here, their Marine 15W40 would be an excellent choice in a car that sees low miles per year: very stout at preventing corriosion.