20/50 SE synthetic. Works better in the summer heat.

 

I have a 2010 Dyna Fat Bob and I'm about to perform a Primary Oil Change and I have a couple of questions.

1) I need to use Formula +, right?

2) How much do I put in?

Thanks everyone!

 

1) NO
2) 1 QT
I just changed mine to Royal Purple MAX-ATF and the clutch is great.

 

I use the same oil in my primary as in the motor - Mobile 1 syn. 20/50
The correct oil level is when the oil reaches the bottom of the clutch diaphragm spring. For my 88 it's usually about 26 oz.

 

Your bike has a wet clutch Any good ATF will work fine. A good fluid like royal purple or trick shift if you want to spend money. Dont overthink it too much. Just drain fluid(overnite if you can) Dump one quart in and be on your way. Motor oil is not a great primary fluid/lots of guys use it. But you will get a bunch of diff answers....

 

I agree 100% motor oil belongs in the motor not the tranny or primary. I have a theory as to why HD does it. and that is they need to only plumb the factory for one type oil, Wich means only one pump / Bulk storage tank etc... Make sense from cost saving stand point for them. But i not sure that the real reason they do it. But ATF in primary , Gear oil in tranny & Motor oil in the motor . You dont see auto manufacturers telling you same oil in every hole do you?

 

Use the formula +. Also in transmission. It is a straight weight non detergent oil without the additives designed for cars which can be corrosive to yellow metals (sleeve bearings) . Since there are no filters, you do not want oils with detergent additives. The magnets on the drain plugs are damage indicators. ATF is way too thin for your inner primary roller bearing. Even most ATF makers say so. ATF is a high detergent and the automatic transmissions have filters and a high pressure oil pump. Use the dip stick for the transmission and bottom of the diaphragm spring as per my attachment. You need to buy total 2 qts for transmission and primary. A little left over. I personally would do both once a year and the engine twice a year if I rode a lot. However, I do mine once a year or so and the filter ever other time, and at 40K it still runs like new. Just for the engine you can save a few dollars on the 15-50 SYN Mobil 1. Since the Harley engine is separate, you do not need the Mobil 20-50V-Twin is designed for metrics that share the oil. Sorry I got carried away..you know oil threads.

 

Use formula +, I use it too. You will need a quart or maybe a little less if you don't drain the old stuff out completely. Get a flash light and shine it down inside the case so you can see when the oil level just touches the outermost portion of the clutch, I usually let it overlap maybe 3/32" at most. Bike needs to be standing straight up and level. It helps to have a soft flexible funnel to get the oil in there, a few dollars at autozone

 

I had M1 v twin in the primary previously, I could feel a little clutch slippage under hard acceleration under heavy load. It also clunked into 1st, which it doesn't do any more with ATF.
And I am pretty sure automatic transmissions have bearings in them, that are lubed by ATF, and seem to last for awhile...

 

Thanks everyone! You guys are the best!