I see alot of space dedicated to which is best for their Harley.
As a veteran and owner of an automobile repair business for many decades I've studied oils and been to many classes and seminars on the lubricants and fluids we use in the industry.
This doesn't in any way make me a expert but rather an experienced observer

Base petroleum oils all start out the same. Synthetic oils are a bit different but the use is the same.
They are used as a fluid that is used to develop a package with the ability to lubricate, clean, seal and cool internal combustion engines.

Car oils and dedicated Motorcycle oils are almost identical in that respect with one exception. Dedicated motorcycle oil use a different additive package that is designed to do all of the above mentioned without adversely affecting the wet clutch that most motorcycles use. In most cases the transmission is also lubricated with the same oil same oil so some additives are added for this good or bad.

In the case of harley we forget that none of the engine oil ever comes into contact with the clutch or transmission. Any modern oil that can be used in any engine can be used in our Harley as long as we use the correct weight.
Our harleys use tapered and roller bearings that need heavier oil to keep film strength up than shell type bearings and the heat our engines produce is far in excess of liquid cooled engines.
In some cases we may be hurting ourselves by using motorcycle oils because they contain additives that we don't want in engines and do contain additives that are at the best useless but may even comprimise the best qualities of engine only oil.

All brand name engine oils are so similar in makeup that it's odd that we have dozens of choices in brand alone.

If you took two identical bikes and changed the oil at 2500 miles and used the factory filter
using the same brand of 20w50 oil in each with one using syn and one using dino I would bet a coke both will go to 100,000 miles without a single oil related failure.

 

Oh Boy Here we go

 

Papaseven, There are differences in oils that are more then just slight. Harley's brand of oil and Redline's brand have completely different amounts of additives. Amsoil has what they believe is the right recipe for long motor life. Some oils shear more then others, and use different amounts of detergents. While others get thicker as the oil gets used. If your interested got o the "Bob is the oil guy" site and you can read all about oil weights , types , brands, voa's and uoa;s., oil change intervals ,and who makes whose oil. Not just for bikes ,but cars,trucks, boats ,lawnmowers and planes.,

 

 

Not trying to put you down here but this is very basic stuff you are talking about that has been discussed to death here. I'm not sure if there was a point in there you were trying to make. Are you saying all oil is the same? or it is ok to use car oil? or synthetic and standard do the same job?????

I use Amsoil because it tastes better than the others and I like to spend money.

 

Um...wrong. Read your manual.

 

I've read on this forum some guys use car oil and have been for a long time. It'll work, I doubt the motor knows the difference.

 

Yep; Many a EVO has gone over the 100,000 mile mark with Castrol GTX 20-50 dino. The proof is in the pudd'n as they say.

 

I use car oil.

 

Very brave but I like the topic been using syn 20/50 tried Valvoline 20/50 syn mocyle this last time just because I guess.