I asked this some time ago and got similar answers. On my first two bikes, I did it because the dealer did it at every 5K mile service interval. On this bike, I follow the owner's manual. But really, transmission fluid is $7.99 a bottle for the HD Formula+. It's not that big a deal, especially if you do it yourself.

 

If you are really concerned about the quality of the oil coming out. It's simple do a couple samples at different miles and have them tested. On heavy equipment and OTR trucks they do them alot to make sure they are getting what they need. How ever they are dealing with many gallons not quarts of oil.

 

I consider the "engineering I paid for" that went into the maintenance schedules, a pointless non-issue. Bad engineering in the automotive world is common enough that I don't think second guessing engineers is automotive heresy. Also, HD engineers recommend HD oil only and intervals which suit it but oil engineers recommend something different which relates to the product their employers sell. "So much for the engineers".

I've done my share of reading about oils and all its peripheral issues. One tenet stands out above all others. "Changing out the oil 100% offsets errors in estimates of package component depletion and all other wear estimates". For most this degree of second guessing has proven totally unnecessary but I'm concerned with my ride not most rides and its my money. There is no down side I know of in uber frequent oil changes. If parsimony is the only reason to stretch service life of a couple of jars of oil to the max, I'm inclined to consider myself fortunate that these $ amounts don't much concern me. I don't run my tires to the wear bars either. The piece of mind I get "knowing" I'm well within the service life of elements like these is of more value to me than the incremental annualized costs of doing things a tad early. Thats just me.

 

Do my own....cheap insurance. If I want to look at the magnet on the drain plug, I might as well change the oil. The cost of a quart of gear lube, and an O ring wont kill me. I **** away more money than that at the Gun Range in ammo every week. I don't have to do that either!!

 

Maybe you haven't read about failures because people are changing the oil more frequently than recommended? Something to noodle over.

 

Um.... OK, if you believe this, go for it...

Although a lot of people base their personal maintenance interval choices on old, outdated info and/or urban legends... it really can't hurt to have an interval shorter than recommended. At what point it truly becomes just throwing money away, can be debated...

Manufacturer maintenance recommendations only matter to keep your warranty in place. Fact is, I suspect most maintenance recommendations are more based on marketing and/or mitigating warranty costs.... NOT what is best or acceptable for the machinery...

This is not a Harley issue, it's across the board for most/all vehicle manufacturers...

Case in point... I own a RAM truck with a Cummins diesel. RAM requires (to maintain warranty) that you change the oil in the engine every 15K miles OR 6 months, whichever comes first..... So if you are an average 15K per year driver, you are changing oil every 6 months, which is half the service interval recommended by Cummins.... Cummins, who builds the engine, says 15K or 12 months.... At 3 gallons per oil change, me thinks that RAM is trying to drum up business for their service departments, and avoid major warranty claims if someone decides not to change it every 6 months...

In any HD or other manufacturer spec based on actual engineering or wear test data, I would expect that whatever they recommend, is on the early side. I'm sure they have a 20% or 30% fudge factor in their recommendation. In addition, time and/or "severe duty" figure into change intervals....

For those that change early, it's just a quart here or there, it really can't hurt...

If someone wants to change all 3 holes at 1000 mile intervals, and they only put on 3000 miles a year... that makes sense, especially if they have to store it for the winter...

So I would suggest to use the manufacturer recommendations, as a minimum, to maintain your warranty. If you feel you need to do it sooner, that's your call...

 

Ooops,

Meant to say "1000 mile intervals and they only put on 1000 miles a year.."

 

I change all 3 holes when I service my bike, period!! I do it because I have a huge investment, I enjoy it and the cost is minimal. I also use a scavenger to remove all the old oil from the engine. I also clean the air filter when I am servicing the bike. My tire pressure gets checked weekly and I like to keep my bike clean. I think it is pride of ownership of a great piece of machinery.

 

Couple of thoughts. If you do it yourself , only the cost of two quarts and two o-rings. There is no filter, so there is a lot more metal floating around in there, so you may get lucky and some of it comes out.
If you have to pay someone, do what the service manual says.
If you do do it, do not overtightened the plugs. Just hand snug and a little bump. Steel in aluminum with oil on it at the recommended torque is too tight to last 20 years. And always use non detergent gear oil in both.

 

Maybe the sentence above about the alleged engineers is the reason for the Trans oil transfer issue, no sense................