I have always ran Syn3 in all 3 holes except one time I tried Mobil 1.
With the Mobil 1 the engine was the same but primary seemed a little noisy and the transmission didn't shift as smoothly as with the Syn3.

I thought I was imagining things so I drained the primary and transmission and put Syn3 back in and it differently was quieter and shifted better with Syn3.
I realize others have not had the same results so it is only "in my opinion" that Mobil 1 isn't as good in the primary and transmission as Syn3.

Now here's were my comment more relates to this thread.
I picked up 9 qts. of AMS 20/50 and 3 qts. of 75/90 yesterday for $90.
At $7.50 a qt. I thought it would be a good time to try AMS products.

I'm about 1500 miles from a fluid change but next change I'll be putting AMS 20/50 in the engine and primary and AMS 75/90 in the transmission.
I'll post my results.

 

you won't regret using AMSoil's

 

I'm about to add this stuff in my Fatboy
http://www.everglideoil.com
so, i'll post my results too

 

I looked to see if there was an ootion for 20/50 but didnt see any

 

There are 2 opinions about oil among Harley owners:
1. Buy the most expensive oil
2. Buy oil with brightest bottle label.
I suggest buying most expensive oil WITH brightest bottle label, preferably red with gold stripes. Blue labels are good too, but not as good as red/gold.
Another very important thing to know about oil, it should match color of your bike. Purple bikes should get Purple oil, red ones Redline oil and so on. At least label color should match.
I use oil from Walmart for $12/5 quarts. I am a car engine mechanic and I read service manuals.

 

Eventually, they all turn black LOL

 

I use the oil that seems to work best - the only part of the label I worry about is if it meets spec. Often - expense in some form can provide a better product.

I'm a maintenance and repair professional who's worked for OEMs, with OEM engine providers and large fleets of over 20,000 class 8 tractors on severe extended drain intervals.

 

I used AMSOIL once and almost killed engine of my car. It was about 20 years ago. They advertised it "good for 25k miles". I was thinking: they are definitely lying, probably twice, so it is good to go for 12k.
Somewhere around 8k miles engine of my VW started losing compression. I flushed engine, used some compression boosting additive and engine was OK. I will never buy AMSOIL oil again. Of course I blame myself for trusting stupid adds. I always use dino oils. When i replaced valve cover gasket of my Jeep with about 200k miles, all parts under cover were yellow, not black or brown, they were absolutely clean! I flush engines every other time with 1 quart of ATF.

 

I'm one of those RedLine, (specific to the hole), users.

Both Amsoil and Royal Purple are PAO based oils. RL is a Polyol Ester based oil. Fundamentally thats the difference in these products. Its easy enough to google up the significant, (or minor), differences between PAO's and Esters so I'll spare the thread my loong version and leave that to you.

Product specific differences also apply and are right there on each product's website. As these oils are all in the same ballpark price-wise, you may want to dig into this a bit in order to satisfy yourself with respect to your choice. Again, this is better read from the source than through someone else's opinion. Whatever you read, it will be difficult to miss an overwhelming number of positive reviews concerning RedLine's "Shockproof" transmission product. Its a bit of a "ringer" for RedLine.

"My opinion":

#1. Red Line

#2. Amsoil

#3. Royal Purple

In practical terms this is a mighty close contest but, again owing to close pricing, its significant IMHO that RedLine and Amsoil make not only motorcycle specific products, but products specific to each hole.

 

"I flushed engine, used some compression boosting additive"

Again......WTF are you talking about??