I have been using the Harley filters up until recently, mainly because they are chrome and I liked the look.
One of the best HD mechanics around these parts (he's in Christiansburg, VA) says the NAPA 1215 (which is a Wix 51215) is a better filter than the HD filter. Wix makes a chrome version of this filter, but it costs more than the Harley chrome filter... He likes Castrol 20W50 car oil for the engine, you'll be happy to hear.
The Twin Cam engines have higher oil pressure, and can therefore take advantage of a finer mesh filter. The HD Super Premium filter has a 10 micron mesh, while the standard filter (the one like my Evolution engine uses) has a 30 micron mesh. So the Super Premium will filter out particles that the standard filter will pass on. The Evolution engine's lower oil pressure calls for a little less restriction at the filter (so we're told). If I'm informed correctly, the Wix and Napa filters have about 16 to 20 micron filtering--so they sort of split the difference. Many oil filter experts say not to read too much into the micron number, so take all that for what it's worth.
My plan is to get a "cool can" as it's called, which is a chrome or bright aluminum slip cover which has cooling fins on it. This slides over the filter. That way, I can use the lower cost NAPA 1215 filter (which is black in color, by the way) and not compromise the looks.
The HD Primary Chaincase Lubricant is a 10W40 motor oil. Some folks have actually used automatic transmission fluid here with good results. The 30 weight oil would probably do fine as well. All that the primary oil does is cool the chain and lubricate it. It's not under an immense amount of stress, and various oils will work. If you believe that moly is bad for the wet clutch (Harley apparently does) then you'll want to avoid oils with much moly in them. I used some leftover Mobil 1 15W50 "redcap" in my primary for a couple months, and did not have any trouble at all with the clutch slipping. That oil has nearly 100 ppm of moly. But I think in the interest of playing it safe, avoid moly heavy oils in the primary. Again, Castrol 10W40 shows almost no moly in tests. Nor does Shell 15W40 Rotella. Both are good in the primary.
If your tranny lube is working well, you'll continue to have good shifts. When it shears and needs changing, you'll feel the difference in the shifting.
I like to try to change the oil at 2500 mile intervals. But as of late, I've actually been doing what I call an "A service and a B service," which is I change the engine oil at 2000 miles and the primary and tranny oil at 4000 miles. (Every other engine oil change). If I forget to do it for 1000 miles, no big deal.
A bud who has a 2002 Low Rider with 41,000 miles on it actually went about 7500 miles on HD 20W50 oil. He "forgot" to change it.
It was about a quart low when he did change it.
That was about 10,000 miles ago, and it's still running great. But I would like to have seen a UOA on that stuff...
Dan
