I agree with 2 wheeler.
Straight 40wt full synthetic, Royal Purple.

One advantage with full synthetic (if you see this as an advantage) is IF there are any marginal gaskets/seals on your engine, it will leak.
So like the old wive's tale... It is best to use full synthetics from new in any sort of engine. Switching from Dino oil to a synthetic will almost always begin to show leaks after the Synth has had a chance to loosen the sludge deposits that were in effect, sealing your cases.
I live in Florida so 40wt is a better choice for air cooled engines. If I was in colder climates I would switch to a 30wt in colder months.

I'm about to change the oil & filter in my ride. I have recently read up on Amsoil. It sounds fairly good. I have a 2006 Sportster 1200 with a trike kit (game leg ) They make an oil change kit for mine. It consists of the required amount of 20/50 synthetic & a chrome oil filter. I just wanted to know if anyone has had any trouble with Amsoil! Being from NE , I had never heard of it. It seems very popular (especially with the racers) here in Florida! I bought the bike used at a Harley Dealership , so I don't know what was used in it before. Any negative results would be appreciated. Thanks!:thanks::yay: Irish:scoot::nuts:
P.S. The HD Dealership took it as a trade in on a NEW bike. Naturally they won't give you any information on what was done to the bike! Whoever put the trike kit on did a good job! To the point of overkill! Having owned two Motorcycle Repair shops in NH , that's one of the 1st things that I inspected. You would not believe some of the trikes that I worked on. I didn't really want to Test Ride them.

Hi Irish,
As I just stated above, switching to a full synthetic WILL show case leaks if anything is marginal. It may take 1-2-3 hundred miles or so but they will show.

There are several manufactures of Synth. oil that have addressed this on their web sites so this is not just a matter of "my opinion".
On the plus side, if you do not show leaks or if you do, and repair them, you will know that your engine is as clean as it can be as well as being protected.

I am a firm believer in Synth. oils for the advanced wear protection they provide along with the improved mileage, and extended oil change intervals. They do pay for themselves in the long run.

Edit:
Forgot to really answer your question.
Amsoil is one of the top brands in oil. While I have never used it, I do know several people who do, and like any top brand oil... no lubrication related problems.
I think this holds true for any major brand of 4t oil

Because I've been riding (& buying parts) for so many years maybe I'm living in yesterday , when it comes to prices! I bought four qts of Amsoil (20/50) & a filter yesterday at a motorcycle repair shop & I could not believe the price! I wanted to try Amsoil but it must be liquid gold! Of course in NH I knew where to go for everything & here in Florida , it's like starting all over again. You don't know who to trust or who to do business with.:s:shrug: Irish:scoot::nuts:

This is not a recommendation! There has been an add on TV in which Mobil One has an oil that you only change once a year!:tdown: Irish:scoot::nuts:

10-30 Mobil 1 here. Seems to do alright. No leaks. 75-90 valvoline syn in the tranny.

Snake oil? Oil change once a year might not be so bad... if you don't ride very many miles during that time IMO. For a car with a filter that can actually keep tiny bits of bad stuff out of the oil flow is one thing; a little machine that maybe only has a SS screen to filter crud out (and barely effective at that!) is something completely different. From what I gather, cheap oil (as long as it meets or exceeds the bike's requirements and gets changed often enough) should be OK. What seems important is that the oil not be too contaminated or broken down to the point of not being able to provide proper lubrication.

BTW Old Man, I use 10-30 Mobil 1 and Valvoline 75-90 synthetic in the final drive gear box of my Honda Reflex 250 too.

Hey, where in Michigan are you?

I ran 20-50 amzoil in tranny and crank in my 09 1200 Sportster and it never had a problem. I started with Amzoil after 500 mile break in and ran it till I sold it with 14k.

grand Rapids

I recently changed the engine oil to 20/50 Amsoil & so far NO problems!:tup::clap: Irish:scoot::nuts:

Amsoil 10-14 metric

I use Royal Purple 10W 40 Full Synthetic in my 2008 CF Moto Fashion 250. Have never run better since the switch.

Right on man, Love the Signature.

I live in Oklahoma, which very warm, and I use Royal Purple 10w 40.

Amen to that.