Dexron 3 is a no-no as it has the modifiers and will cause clutch slip under high load. I use an older grade of ATF (automatic transmission fluid) without the friction modifiers (type D or F). The oil is in there to pull heat from the primary drive chain and to lubricate the chain and clutch plates. You can actually use almost any oil in the primary as long as it does not contain friction modifiers. I've found that it is not enough, 32oz (1 litre) will fill the twincam primary to the proper level on my '05 softail. The manual recommends 26oz (770ml) of primary chaincase lubricant. There's an old saying that goes "Oil and filters are cheap, motors are not". I've found halving the service schedule for fluid and filter changes will let your bike live long and strong.
The service manual recommends changing the primary oil every 5000 miles (8000 kms) but I halve the intervals on my personal bikes. If you're reading this then you want to change the primary oil yourself and its a really easy job you can do at home with a few basic tools. Its saved me a shitload of money over the years and I know the job is done right. I work on my own bikes and cars and have done for the last 25 years.
Harley transmission oil leak how to#
HOW TO SERVICE THE PRIMARY IN YOUR HARLEY DAVIDSON TWINCAM SOFTAIL.
***This pictorial how-to takes a while to load on your PC but its worth it!*** DUDEWORLD - HOW-TO TWIN CAM HARLEY PRIMARY OIL CHANGE