There have been several threads discussing using motorcycle oil vs regular motor oil in the engines of these bikes. Many are using the Mobil 1 15/50 because is costs a bit less and it will work fine. I've mentioned in some threads that either will work, the motorcycle oils are just designed a little different based on the needs of the application. Minor differences, but some non the less.
For amsoil users of the cycle 20/50 that might be thinking of trying the regular motor oil, just wanted to be sure you were aware that amsoil also has a 20/50 motor oil
It will save you 10% or more over the cycle oil.
Just an option. I myself don't chose to use it. Price would be the only reason to switch. The $20 bucks I can save I've have spent 5x over the next time I walk in the harley store doors

 

What about this new 20W50 motorcycle oil with the zinc added? Is it better choice of the 3 20W50 you folks make. Buy the way really like the regular 20W50 MC Oil. Been using it since day one.

 

The 20/50 motorcycle oil is the product of choice. The 20/50 motor oil with the link above does have a high zinc content compared to many oil on the market. It does not contain friction modifiers so it could be used in the primary, but does not have a GL rating, so would not use it in the tranny at this point.
This weight of oil isn't used much anymore in the typical engine, mostly for higher performance, especially those with flat tappet cams. Lower zinc content oils have shown to be problematic in flat tappet applictions.
The only other 50 weight we have is the new 15W-50 racing oil. This would also work but is a bit overkill for this application
.

 

Heath,
You advise not use the 20w/50w in the transmission but Amsoil reccomends this as thier 1st choice for both the Evo 1340 and Twin Cam . Any insight?

 

No, trying not to confuse here. The cycle oil can go in all 3. The ARO engine oil could be used in all 3 but it does not have a GL rating, so I wouldn't use it in the tranny.

 

Heath thanks for explaining.

 

I've seen three oil tests in three different MC mags and all of them basically concluded that motorcycle-specific oils are not worth the high premium that you pay for them. I ran a 20w50 synthetic "car oil" in my old RK and it is still running at 120k miles with no engine work. A friend performed a big-bore upgrade on his 2000 EGC a while back and after 60k miles running 15w50 M1 the cylinders, pistons, and rocker hardware showed no visible or measurable wear.

 

All the 'scientific studies' are interesting, but after a while I start to wonder how much of the test results are for bragging rights rather than what is actually needed by our engines.

I've mentioned many times before that the majority of guys I know with high mileage bikes (a few EVO's but most are TC's) run regular synthetic Mobil 1 15W50 motor oil, the same stuff that I can purchase for $4.20 a quart in bulk.

Most of these folks ride 20,000+ miles a year and many have well over 100,000 trouble free miles on the original engines. And this is in the lower midwest where temperatures of 95+ degrees are normal during the summer months. (Lately we've been having 100+ temps with the heat index over 110).

Maybe regular ole synthetic Mobil 1 15W50 doesn't rate as high in the 'bragging rights' department, but apparently Harley engines aren't very smart and don't realize that they are being mistreated.. Change the oil and filter are reasonable intervals and they are perfectly happy, even if they aren't being fed high dollar "motorcycle specific" oil...