My service manuals say 20K. My Corvettes were ATF and lifetime no changing.

However, when it is an air cooled HOT engine sooner is better. If you cant handle the cost of a qt. of trans oil, you need to sell the bike as gas costs way more in the typical 5K a year rider going 4 years and needing one quart on HD trans oil. That would be about $2/yr.

Good God worry about something important like mineral oil or syn, if syn what brand.

 

I like clean fluids, its easy and only takes a few minutes.

 

I should have known better....but I asked anyway.....

I am not worried and I can afford the oil.....it was mere curiosity that has me thinking about the shorter change interval.

I see no reason why an manual transmission would be cooler on a bike....neither car not bike manual transmission has separate cooling that I am aware of. An Automatic transmission like on my Allison is a separate matter and I am not going there.

Just wondering why the oil life is claimed to be so much shorter on a harley manual transmission than a car or truck.

 

oh...and BTW ....I am an untypical 15000 mile a year harley rider.

 

Lets see -- transmission oil change approx. 75,000 miles -- the oil looked the same as when I put it in

Primary -- about every 25,000 to 30,000

Engine -- filter at 7,000 complete change at 12,000

bike has 100,000 miles on it -- I guess my service interval works

I got bike (a 2000 model) in Nov of 2006 with 6,000 miles on it -- so I have average 15,000 a year some years a bit more

 

I like to recycle, so, every 5k I re-cycle my fluids:

I put the old engine oil in the primary, the old primary fluid in the tranny and the old tranny fluid in the engine. I change all 3 and the oil filter every 20k.

I've had no problems. My engine runs great.

 

The manual says engine every 5,000 and the primary every 10,000 and the trans every 20,000 miles. I use synthetic and plan on doing the engine every 5,000 and both the trans and primary every 10,000 because it will be easier to remember.

 

I'm not saying this is WHY, but some things to consider are that the components in your Harley's transmission are much smaller than those in a auto or truck transmission, and have higher operating speeds. Also, the Harley transmission holds much less oil than an auto or truck trans. These factors could cause the oil to be "worked" more than the oil in an auto or truck transmission. Keep in mind too that the MoCo is assuming that you're running Syn3 or Formula+ in your bike's trans, even though many Harley owners run 90w or heavier hypoid gear oil. I hate it when motorcycle transmissions puke, so I don't mind changing the oil every 5K miles.

 

you might want to recheck your service manual. according to my hd touring manual for 2010, first oil change is at 1k, then every 20k thereafter. primary is at 10k intervals.

i used to do it that way, then i got into the habit of doing the engine and primary every 5k. i would adjust the clutch the night before and then do the oil change the next day when i could get it up to operating temp.

 

Let me as an engineer explain some things and myths about 'oil change'.
First of all it depends of the application of the oil. Is it only transmission oil, is it engine lub oil.
The next question is, is it fully synthetic oil or mineral oil?
To start with the beginning:
a the purpose of any oil is - cooling
- lubrication
The transmission oil has the same tasks, viz. prevent physical contact of metal-metal of the parts (gears, shafts, bearings)
Depending of several conditions the oil is 'wearing out' or better said: 'loosing its lubricating capacity"
One of the first conditions where alle the others are depending on is : mechanical load of the gearbox. Are the forces between the teeth of the different gears high, moderate or low. In the case of a HD these forces are objected as 'moderate'. 'Low' when it depends on the quantity of HP's passing the gears but 'high' considering the torque transferred by the gears. Depending of the load the temperature of the oil will raise, limiting the life span of the oil. Two factors, indicating a change interval. In the case of HD I would say, depending on your style of riding (mechanical forces onto the gears) and the ambient temperature (temp rising of the oil) I consider at least 10,000 miles as 'very acceptable' for transmission oil. In cooler climates and a low mechanical load 15,000 miles or more could be done without any problem. On the condition that 'full synthetic oil' is applied and no very old fashion 'mineral oil', although in some cases the mineral oil is preferable above synthetic oil.
The engine oil has approximately the same conditions to work under, with exception of the temperature which is much much higher than with transmission oil.
Because of the carbon parts of the combustion (collected by the oil, because cleaning by the oil of the carter, bearings and internal cylinder surface is one of the extra tasks of the engine oil. 'Heat' reduces the life span of the oil considerably, contamination with carbon particles and metal particals (removed by the oil filter) shorten the life span of an engine oil as well. I would consider no other oil than 'full synthetic" and no longer than 8000-10000 miles, depending of the temperature and the riding style.