Marty said:
Posting a link with misinformation on it does not change the way an oil pump works. Do you know what "positive displacement" is? The oil pump will pump a fixed volume of oil per revaluation period then end. Oil will not compress as filter resistance goes up. The oil pump speed will not go down as oil filter resistance goes up. Simply put you are wrong to suggest that the standard efficiency OEM filter has a flow advantage over a more efficient and more restrictive premium oil filter such as a pure one. If you need cold starting flow then use an oil of the appropriate viscosity for the temperature in question.
Dallara you are one of the smartest and most knowledgeable people here, and I say that with all sincerity. I have learned a lot from reading your posts. That said I am amazed that you would use a less efficient oil filter for better fuel economy and less pumping loss.
Marty said:
Last I checked, Shell Rotella oils are the only non boutique brand oils that meet JAOSA MA standards for motorcycles with wet clutches. It is interesting that some oils "marketed" as moto specific oils do not meet JASO MA standards.
Marty said:
Dallara ck out this description of how positive displacement oil pumps work.
Quote from the link:
"Positive Displacement Pumps, unlike a Centrifugal or Roto-dynamic Pumps, will produce the same flow at a given speed (RPM) no matter the discharge pressure."
http://www.engineeringtoolbox.com/positive-displacement-pumps-d_414.html
First off, thanks for the kind compliment. I hope I help folks here, at least some of the time. ::025::
And yes, I know what a positive displacement pump is, and how it works... and quite well, thank you.
But by the same token, I would hope you know how oil filters work, and what an oil filter bypass valve is. For those of you who don't here's a great explanation from
http://vfrworld.com/tex_vfr/tech/filters.htm ...
"The Bypass Valve
First you need to understand why the bypass valve is there. Under *ideal* conditions, the bypass valve will *never* open. Because, when it opens, the oil *by passes* the filter and goes on through to the motor, obviously unfiltered. It is a safety valve. However, in *real* operation, it opens often.
1. One example is when you start the motor when cold. The oil is thick and does not pass easily through the filtration medium, thus building up to a high pressure drop. So, the bypass valve opens to prevent oil-starvation of the motor. How long it stays open is dependent on how cold the oil is and how long it takes to get near operating temperature. When the pressure drop across the filtration medium drops below the bypass valve setting, then the bypass closes. Blipping the throttle while warming up is a good way to get the valve to open and send unfiltered oil to the motor. A steady warm-up rpm is probably a lot better.
2. Another example can occur when the motor is fully warmed. At idle, the oil pressure is about 15 to 20 psi, and the pressure drop across the filter is about 1 or 2 psi. You take off towards the redline, and quickly build oil pressure to the 70 to 80 psi range. During that full-throttle acceleration the pressure drop across the filter will exceed the bypass setting, and send unfiltered oil to the motor, until the pressure across the filter has time to equalize. During a drag race, shifting through the gears, the bypass will open several times.
3. A third example, which you should never experience with frequent oil and filter changes, is when a filter becomes clogged. A spin-on filter can commonly hold 10 to 20 grams of trash before it becomes fully clogged. The bypass valve opening is the only way to keep the motor from becoming oil-starved if the filter becomes clogged.
According to Purolator, the Honda OEM filter bypass setting is 12 to 14 psi, and that is how they build their motorcycle oil filter. WIX (NAPA Gold) builds their motorcycle and automobile oil filters with a bypass setting of 8 to 11 psi, while AC Delco builds theirs to a setting of 11 to 17 psi. How much do these differences matter? I don't think anyone knows, even the engineers, and each has its own set of advantages and disadvantages.
• If you do lots of racing, you're probably better off with a higher bypass setting.
• If you do lots of *cold* starting, especially in the winter, or seldom change your filter, I think you're better off with a lower bypass setting. However, with few exceptions, bypass pressures for spin-on filters run in the 8 to 17 psi range, and any of them should work acceptably."
Now, a couple of important points, at least to me and my motorcycles...
Note how even Purolator states that Honda's filters (made by Denso, the same folks who make Yamaha's filters), including their motorcycle filters, open their bypass valve at 12 to 14 PSI, whereas certain filter makers who manufacture primarily for cars have their bypass valves operate at a lower 8 to 11 PSI, and often times these same auto filters have denser, more restrictive filtering media (and just because it's denser doesn't mean it filters better - it depends on the media - but you know this...), the type that causes that pressure drop across the filter we discussed earlier. What this means is when your motorcycle engine starts up cold those filters are more likely to have their bypass valves open up and let unfiltered oil circulate through your engine... whereas that "standard efficiency OEM filter" that "has a flow advantage" is less likely to have it's higher pressure bypass valve open, and as such will be filtering your oil right from start-up.
Once everything is all warmed-up and at operating temp all of this probably doesn't matter... But since the vast majority of engine wear occurs in those first few seconds after start-up and those minutes as the engine reaches operating temp any reason that might cause that bypass valve to be open any more than necessary does concern me.
So yes, flow vs. filtration in a filter interests me, still...
As for using "an oil of the appropriate viscosity for the temperature in question"... I use primarily 20W-50, just as Yamaha recommends on page 9-1 of my Super Tenere's owners manual for temps of 50º to over 110º F. Here in South Texas most of our riding season is done above 70º F, and during the summer (like now) the temps are often over 100º F, with actual road temps much higher (i measured an asphalt pavement temp of over 150º F the other day with an infrared thermometer at the end of my driveway). If I happen to hit an oil change interval right in the middle of our winter (December and January), or I know I'm taking a ride into colder climes, then I will use 10W-40, just as Yamaha recommends for temps from 10º to 110º F.
And yes, I use Mobil 1 full-synthetic motorcycle-specific motor oils, and both their 10W-40 and 20W-50 are JASO MA rated (you did mean to say JASO MA, and not "JAOSA MA", didn't you?).
Hope this helps!
Dallara
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