2012 Road King. I've been changing Engine Oil and Filter with Syn 3 and Primary with Formula +. Changing Trans. at 10K with Formula +.

1. Any concerns or comments on that?
2. Why is it important to change the Primary on the same schedule as the Engine?
3. Why is it important to change the Trans. at 10K. Seems like low miles for that type component.

Appreciate your input.

Thanx.

 

I'm not a professional but I assume it's because engine oil and your primary will go through more heat and go through more hell in cylinders than your tranny.

Good question though. Anyone know for sure?

 

Personally change all 3 at same time, just feel is cheap insurance.

 

You don't have to change the primary at the same time as the engine oil. Harley Davidson says to change the engine oil and filter at 5,000 miles, the primary at 10,000 miles and the transmission fluid at 20,000 miles.

 

Engine oil is contaminated with the by products of combustion that use up the additives. It also makes the oil acidic. I run a full synthetic 5 k miles. If I were using conventional 20/50 I would change at 3 k miles.

The primary also has contamination in it. The clutch plates shed material into the fluid as they're engaged and disengaged. It's also a very hot environment. Besides friction material, modern Harleys also have metal in the primary from inherently weak compensators. I would change it every 5 k miles.

Transmission oil isn't contaminated by anything and if you use a full synthetic as I do (Spectro 6 Speed) it will easily go 15 k miles. HD transmissions benefit from good transmission fluid and the good stuff is easily capable of 15K. Dropping a good synthetic trans fluid out the drain plug at 3 to 5 k miles is wasteful.

 

This is what I've read more times here, than any other way of doing it.

 

Do you all change oils yourselves?

 

Your choice of oils seems to work for thousands of bikes so I wouldn't worry about it. If you wonder how any of the oils are holding up, you can send samples to Blackstone labs for a used oil analysis. It tells you how much wear particles are in the oils, and if the oil has sheared grade, or too much gas in it, and how much life is left in the oil. The primary oil will have clutch dust particles in it, but for that compartment is normal. Trans oil usually looks like new, no matter how long it's been in there, but you should still change it when it has enough miles on it. If it doesn't look like new, or has silver metal flakes in it, that's a sign you have problems.,,,,

 

I'm the only one who touches my bikes apart from warranty work and neither of my bikes are under warranty. That said, I have my machine work done at a place in Florida called Vee Twin Racing.

 

I switched to Mobil 1 V twin 20-50 mostly cause it's easy to find and usually on sale every spring..

I have also used it in all three for the last 38K ( without a single issue),, I change the engine and Pri every 5K and the tranny Once a yr cause I usually ride no more than 10k a year.

Nothing wrong with Formula + in the Tranny and Pri ( I used it for the first 15K)and I have been thinking about going back to it in those two holes...