Originally Posted By: Jim Allen
There are a number of us "Ford Modular V8 folks" here at BITOG. Welcome to the fold!
My opinion as one of that crowd is that as far as winter performance goes, like the post above, I don't see a difference... both have silicon ADBV valves and that's the major winter design feature.
FWIW, I am now running a P1 on my 5.4L in preference to a FL820S because of the higher level of filtration. The base end bypass is indeed a preferable construction element but somewhat overvalued IMO. In valuing and weighing each of those characteristics, my conclusion is that finer filtration is a benefit that pays every day. The base end bypass is harder to value. Yes, in theory, if a bypass event occurs it's less likely contaminants on the dirty side of the filter will be flushed into the system. The questions to ask are:
1) How often do bypass events occur?
2) Under what circumstances is a bypass event likely to occur.
3) Why do almost every other filter manufactuer (included the very top end,best, most whizbang and highly rated) filters still use a dome end bypass?
My answers:
1) Almost never.
2) Most likely on a cold start, or first startup after an oil change, and in either case, the event is momentary. In such an event, the likelihood of much contamination being flushed off the filter is minimal.
3) Because they don't see it as a necessary feature... for the reasons above and likely others.
In my perfect world, you would be able to get an filter with a base end bypass and the general high construction quality of an FL820S,but with the media of an P1 at the cost of a P1. Since I have to choose between features, again, I choose the feature that pays daily, the better filtration.
PS and FYI- I finally have all the pieces now to install a Racor ABS bypass system on my 5.4L. It will have a 3um absolute filter in it. I have one more P1 in my stash to use and after that, I will probably switch back to FL820S.
You'd be better off with the FL820s year round. As for the frequency of oil filter bypass mode,
1. It happens far more often than people realize. From charts I have analyzed from my work at SWRI, most filters will go into pressure relief mode when the temperature drops below 40F @ 2 - 3 gpm (5w-30) with a clean/fresh oil filter. For some vehicles (especially, VCT types) the oil filter will go into bypass right off the idle at these low temperatures and will most definitely bypass during cold engine start.
2. According to Fram, the pressure relief valve is expected to open anywhere from 20k to 30k per OCI, mostly from cold start-up.
3. Ford claims that contaminants too large to embed into the oil filter media and oil suspended wear causing particles will settle out of suspension and fall against the oil filter shell. Upon start-up, these wear causing contaminants are immediately bypassed into the engine. A portion of the cold-startup wear is attributed to these contaminants.
It is cheaper to make a filter with dome-side bypass. As far as I know, only Ford claims it is important to have it on the threaded in. I think it does matter in terms of engine longevity. But I also believe the OEMs have a calculated wear rate for their engine designs under recommended maintenance to achieve a target engine life. From the reports I have read regarding OEM engine testing, OEMs tend to stop testing at an equivalent of 150k miles. But with almost everything engineered, there is a margin of safety; so a well maintained engine should exceed 150K miles. I believe Ford's FL820s is the best option for modular engines.