Syn3.

 

Syn3 was factory filled in my 2007 Heritage. I find it hard to believe that non CVO M8 motors are filled with non-synthetic oil. You can’t even buy a new car today that doesn’t come factory filled with synthetic oil.

 

believe it..the statement below from my Owners Manuals is the same as long as I can remember and Formula+ trans and primary..and SYN is listed as an alternative..CVO's have stickers on the engines stating they are SYN3 factory filled

This motorcycle was originally equipped with GENUINE HARLEY-DAVIDSON H-D 360 MOTORCYCLE OIL 20W50. H-D 360 is the preferred oil under normal operating conditions. If operation under extreme cold or heat are expected, refer to Table 1 for alternative choices.
If H-D 360 is not available, add oil certified for diesel engines. Acceptable designations include: CH-4, CI-4 and CJ-4. The preferred viscosities, in descending order are: 20W50, 15W40 and 10W40.

 

Thanks, I should have read this in my owners manual before I posted. Since syn3 is better suited for lower temperatures it sounds like cost cutting on HD’s part, so I will be switching to syn3 in th crankcase at my 1000 mile service. Is there any reason why conventional oil would be better to use in a M8?

 

other than cost I can't think of any...We never run Synthetic in our bikes but we live in a moderate climate geographic location so never felt the need to spend $5 more per quart

 

As far as I was told by the dealer, mine came with F+ in the primary, dino in the tranny and crankcase. I have since replaced with dino in the crankcase, red line in the tranny and F+ in the primary.

If I go on a long trip where I know there will be hot weather I will change the crank over to synthetic. I did this on the last 2 bikes I owned without a problem.