NOT A BRAND DEBATE
NOT A SYN DINO DEBATE

Ok? Good

A Harley Davidson big twin does not have a clutch that shares oil with engine. So a oil without friction modifiers is not necessary. That's basicly why motorcycle oils were created because engines that shared oil with clutch couldn't have friction modifiers. They were too " slick" to operate the clutch.

So I wonder why there's such a emphasis on motorcycle oil in regards to harley big twins when motorcycle oil isn't a nessisity at all. And actually what I want to know is....isn't friction modifiers a GOOD thing for a engine??? So if I don't NEED a oil WITHOUT friction modifiers wouldn't I want a oil that does have them since the oil is for the engine only? It seems a oil with friction modifiers would be great for a harley engine and provide more lubrication. It seems in theory that motorcycle oil is " less slick" in order to operate the clutch. But since big twins don't share oil with a clutch it seems running a high quality automotive oil with friction modifiers would be a ADVANTAGE. Am I wrong?

X brand 20-50 motorcycle oil. Designed to run a clutch and lube engine ( most metric bikes)
X brand 20-50 auto oil. Designed to lubricate engine only....not accommodate a clutch ( can be used in harley big twin)

Let's look at Lucas oil. Lucas 20w50 motorcycle oil vrs 20w50 racing oil. Wouldn't the racing oil essentially lubricate better because it isn't designed to allow operation of the clutch????

Please no brand and Dino vrs synthetic. This isn't about that. Simply about automotive oil with friction modifiers vrs motorcycle oil without. In the case of harley big twins a motorcycle oil isn't required at all and I wonder if it's really inferior to a high quality automotive engine oil that's for engines only and not designed to operate a clutch. Just seems to me the " slickness" of the motorcycle oil is reduced in order to occamidate a clutch but with harley there is no need for it.

Yes I know....put in what you want. I will. Just asking out of pure curiosity and educational purpose. Did a lot of searching and never saw this subject dealt with directly. Also this only applies to harley big twins

Im going to try a high quality automotive oil. I'm curious if it will reduce the top end noise I get from popular motorcycle oils. My feeling is if the oil is less slick to run a clutch on a metric bike why should I use it in my harley if I don't have to. The part of the automotive oil that makes the clutches slip is what might make my top end quiet

 

I understand what you're talking about. My only concern would be about how hot our air cooled engines run, compared to a liquid cooled car engine. Perhaps that's why you referenced Lucas racing oil rather than plain old Penzoil or Valvoline?

 

I run conventional Valvoline VR1 50w in the motor in the summer and VR1 20w50 fall thru spring. It has a high zinc content and additional friction modifiers. The gentleman that recommended it to me had over 150,000 miles on his 95 Dyna at the time and hadn't been inside the motor yet.

Far from an expert here, it may not be necessary but I see no reason not to run oil with friction modifiers in the motor.

 

Good subject as I've also wondered why not auto oil in the Harley engine. Yes heat is a concern, but I ran a 79 Porsche 911 at a racetrack where the oil temp reached 300 degrees F routinely. I ran Mobil 1 and had the oil tested regularly. Many times the test results came back "top off, don't change". So hey out there oil experts - why not run auto engine oil in the Harley motor? Subscribed

 

Correct. Wal mart automotive oil isn't part of the equation. I'm talking high quality automotive such as Valvoline 20w50 synthetic racing oil. It's same price as the motorcycle oil but I wonder if it's BETTER oil since it's not designed to operate the clutch

I don't see heat as a issue. A quality synthetic racing oil with high zync rating and friction modifiers may handle heat better than a motorcycke oil that's dummed down to not make the clutch slip. The loss of friction modifiers may be why harley top ends clatter so much. The extra lubrication that's taken away to allow operation of a clutch could come in handy instead of hearing " tick tick tick"

 

Have you looked into the Phillips Aviation 25W-60 made for radial engines

 

You have 20W50 built for wet clutch...
You have 20W50 built for gasoline engines...
You have 20W50 built for diesel engines...
All the same ISO grades but all different base oil and additive packages.

All specific oils (automobile, diesel trucks, V-Twins, etc) have their specific formulas. Now does an automobile oil can do the job in a V-Twin engine ? probably yes, but since those oils are built for engines with cooling systems, they are made to resist to lower temperatures according to manufacturer's specs. Thats why I would prefer to use, as a substitute, a diesel engine oil.
But nothing is better for a V-Twin engine that a V-Twin designed engine oil.

...Wet clutch oil is another story, like transhydraulic and other shared application oils.

 

The "plain old" Valvoline I use actually makes my bike run cooler than the other dino and synthetic oils I've used.

 

But that's enzactly what v twin oil is. It's not nessicarily designed for a v twin...it's designed to run a v twin AND a clutch. All those motorcycle oils are made to dump into a metric v twin that shares oil with the clutch. A harley big twin does not need a special blend to allow the clutch to operate with the engine oil. Yet the oils we use have the friction modifiers taken away in the name of " v twin oil" when the only v twins that need MORE friction are metrics and sportsters ( because of clutch)

Don't get me wrong I'm not bashing motorcycle oil. Just wondering if we can do better since we don't need MORE friction to operate a clutch. Seems less friction would be better in the case of big twins that can get away with it

 

What it comes down to is that just about any oil is gonna be just fine for your bike as long as you use the proper viscosity, even that " crappy Wal-Mart oil", and change it at proper intervals.

I use to use mobile 1 1509-50 that I could get at Wal-Mart for$25 for a 5 qt jug. The only reason I quit is that they stopped selling it in my area.

Use what you like, change it occasionally, and your bike should give you years of service. When was the last time that you heard of anyone having engine problems caused by oil?