Sorry for the length of this. Been hanging out here for a few years. Don't post too often. Have gotten lots of good info just browsing but some that leaves me confused.
Did a complete oil change today - 09 Street Glide 18,000 miles. Used redline in the trans after reading the good reviews here. Used syn 3 in primary and engine. Always ran syn 3 in all holes before as that is what the dealer did on my 1st and only service with them. So, the dealer used syn 3 in the primary, I kept using it, My shop manual calls for primary plus not syn 3. My owners manual said syn 3. The posts here recommend everything from syn 3 to dino to other oil brands. I read reports on here of bad compensators, cam tensioners, etc yet also read that it really doesn't matter what you put in there. Leaves me VERY confused since I want to extend the life of my bike to 100K or better with no major issues and have to believe thaat it must make a difference what you run and how often you change. In the end what is best? After 4800 miles my engine oil looked pretty good coming out. The tranny fluid which was syn 3 before looked brand new after 9000 miles since the last change...nothing but a little "dust" on the magnetic plugs. Now for the primary...Had syn 3 in the primary, 9000 miles as well. This time looked very dirty and in addition to the "dust" on the drain plug it also has very small metal splinters. Never saw that before. Just the dust in the past change at 9000 miles. Is this OK or am I headed for the dreaded plague of compensator, primary bearing or cam tensioner issues I always read about? No noise, shifts good. The last 9000 miles though have been extremely hot commute miles as I battle Houston heat and traffic 50 miles each way to work each day. My first 9000 miles were all touring miles until I had to give up the company car and begin using my own transportation and gas to get to work.

 

Mobile 1 V Twin for engine oil. HD Primary oil. Shockproof light for tranny.

06 SE Fatboy
10 RG

 

After the responces you get here you will be even more confused.

 

You are going to get lots of opinions on this but from my experience I have used Mobil-1 in my primary sense it had 1000 miles on it and now im at 112k
and very few issues fwiw.

 

You will never get a unanimous vote when it comes to oil threads.
It always comes down to personal choice.

It is my opinion that it is much more important to actually perform the service, than worry about what "brand" to use.

 

I use Royal Purple in all 3 holes... Pimpin' ain't easy.

 

So you hope to clear this up do ya. Good luck.

 

LOL, true dat

 

I always change the primary when I change the engine oil at 4k. Primary is usually darker than the engine oil. Use mobil 1 vtwin 20w50 in engine and primary and mobil 1 85w120 in gearcase every 10k on gearcase.

 

My biggest opinion is to CHANGE THE OILS ON TIME! Doesn't matter what you like as long as the bike is serviced when called for ON A REGUAR BASIS!