Recently there was a fairly lengthy discussion on what kind oil to use in your Harley. During the whole conversation I ended up calling Harley and asking them what they thought about us using synthetic oil and whether or not it would void your warranty.

Well, the Jan/Feb 2005 issue of Ironworks magazine has a pretty good article in their Tech Lite section which discusses this very topic. Here is what I learned, and I would welcome discussion from all.

Essentially, Harley has not bought into the whole synthetic thing until recently, and even so, their official literature says that they have never officially tested any brand of synthetic oil except their own in their bikes. So, their stance is, "We're saying our's is better, but we've never tried theirs..."

Ok, well, to cut to the point of this post, the article had 2 major points:

1. Synthetic is always better.
2. Never use anything but motorcycle oil in your motorcycle. (i.e. don't use car motor oil). But there is a caveat to this.

Oil is designed to do three things: Lubricate, dissipate heat, and clean.

Lubrication is important, and the oil actually lines the various parts and acts as a cushion against shock to help separate one moving part from another. Synthetic oils cling better to surfaces than do petroleum based oils.

Motorcycle specific oils have a higher "shear" strength than their petroleum based counterparts...WHY? Because many bikes (not the Harleys) have a shared oil system between the transmission and the engine oil...this is true on most Metric types. Transmissions place a higher demand on the oil, requiring a higher shear protection to maintain their viscosity over the life of the oil. Oils for cars don't deal with transmissions, so here is why you don't want to use car oils for your bike...(even petroleum based oils designed for motorcycles are better than oil designed for your car for this reason).

But wait, Harleys don't use the shared oil (between motor and transmisson), so what does it matter? Well, as it turns out, and many of us already know this, the transmission does have a wet clutch, so in this case, friction is a good thing. Harley's SYN3 and AMSOIL are the only two that Harley has officially given the nod to for their motorcycles. By the way, this wet clutch is why many mechs will tell you not to use the synthetic as the oil is too slick....NOT TRUE if you use the right oil, designed for you motorcycles. Motorcycle synthetics are designed for this purpose.

Heat dissipation is important and is a problem for big V-Twins especially when you consider that the second jug is tucked behind the first one, denying it the benefit of airflow that the front one has. Synthetics don't break down as early as the petroleum based products, which causes the oil to lose it lubricity...

Cleaning is the last. The article cites byproducts that occur from internal combustion: ash, moisture, and unburned fuel as offenders. These contaminents are absorbed into the oil and carried to the filter. What's not picked up by the filter is obviously left in the oil until you change it. As it turns out, evidence from the myriad of tests indicates that the synthetic oils practically stop the wear process of internally moving parts...it's supposed to be that good.

As far as not using it until the engine is broken in...BULL. Harley is OK with that too. My Corvette came with a fully synthetic oil at stock, and in the owners manual and on the oil cap it says not to use anything but synthetic...that engine was built to race...

So, there you have it. End state is this...use synthetic, and if you're going to use the version made for cars...probably shouldn't put it in the primary...

Mac

 

Okaaaayyyyy....

So if I wanted to play it safe use the Harley recommended motor oil and transmission oil?

And for motoroil I should use Harleys SYN3?

So for someone not in the know (me especially) could you please tell me Harleys recommended:

1. Full brand name / oil type for the engine?

2. Full brand name / oil type for the transmission?

I think that even though there may be other options I will just stick to the Harley recommended...

 

I talked to my mechs at the dealership and they said that synthetic was the way to go but not Amsoil because it's thinner and runs hotter than SYN3. Now, I know they have to say it but the mech was straight forward. Plus, I was talking to the lady who does the warranty work and she said that when it gets down the road and you have 75,000 miles on your bike and you're still under warranty, should anything happen you can either say you've used strictly HD oil or you can't and at that mileage it'll make a difference in how they treat your case. I thought that was interesting.

Thanks for the great info, Mac!

 

I'm not really a motorhead but I do know this, after about 15,000 miles, I began running synthetic (Amzoil) in my old Sporty and immediately noticed the difference. It ran smoother, cooler and didn't have the engine "rattle" after the oil got hot.

I just traded for a new Softail and the dealer put in the HD synthetic at the 1,000 mile service. A service guy at the shop that I trust said the only reason not to run synthetic from the get go is that break in oil is only in the bike for a short period of time and there is no reason to go to the extra expense. For me, I'll run synthetic from now on.

 

geezer, I run syn and have no problems. I also change the oil, tranny and primary fluids more often than recommended, always have, and have never had to do a lower end rebuild on any bike I had. I do my own service so the cost is minimal.

 

I used to wrench on cars for a living, and synthetic was always a better choice. Back then the synthetics were REALLY expensive though, and it was cost-prohibitive unless you had a racing enigne or a really high mileage engine that you wanted to keep running. It makes total sense that synthetic would outperform fossil oil in a motorcycle engine... ESPECIALLY an air-cooled engine. Less friction = less heat. It's alos more forgiving if you go over the change interval. Synthetic oil is quite affordable now, so I don't see any reason not to use it. I know I will be running synthetic in my Night Train.

Cheers!
[sm=icon_rock.gif][sm=icon_rock.gif][sm=icon_rock.gif]

 

howartthou,

Harley will only recommend THEIR stuff. They do not have a fully synthetic oil in their line. Fact is, Harley is behind the times on this one. Your bike, you certainly are free to do as you choose. I will run fully synthetic in mine henceforth, this article merely affirmed what many already knew.

The real point of the post is the differences between Car and Motorcycle oils, and the effect on the wet clutch.

Your warranty will be good as long as you use an oil that meets the standard (doesn't matter if it's synthetic or petroleum based)...any motorcycle oil does, so you are good.

I don't have the specific catalog numbers for the various manufacturers of oil...NC BREW did a pretty good job providing the information on a different post Best oil for your Harley thread. Read up on that, and let me know if you have any questions.

Personally I'm still on the fence as to whether or not I'm going to use Mobile 1 or Amsoil, but based on the cost, I will probably go Amsoil.

[sm=icon_cheers.gif]

Mac

 

Well guy's I've got to get in on this topic because I am sort of a oil nut. After doing a lot of research I have found that the HD oil is made by citco,also I have read several article's that say the HD oil's are good but aren't the best in the oil test that they do. Also amsoil is a very good oil but I don't think it's as good as they claim,they buy there chemical's to make their oil's from who?,Mobil1. Amsoil distribator's will even say if I wasn't using amsoil I'd use Mobil1. Go to this site and check it out,lot's of info on oil.bobistheoilguy.com

 

Yep, interesting! She just set the dealer up for a violation of the Magnuson-Moss (IIRC?) Warranty Act. If they treat you any differently with a warranty issue because you used some other oil besides HD, they are screwed. All you have to prove is that the oil you used met the specs HD required. They can't require you to use their oil unless they provide it to you free.

When all this synthetic stuff started with HD, they made a lot of noise about how you shouldn't use it because they hadn't tested it. Well, duh! Why should HD test others' oils?

What ticked a lot of riders off was they didn't do much in the way of correcting their dealers who spouted garbage about disallowing warranty claims if synth was used, or that synth was so slippery that roller bearings would slide, that it couldn't be used during break-in or the rings wouldn't seat, and several other ignorant claims. They lost credibility with me, and dealers who refused to even consider evidence to the contrary did so, also.

I quit dealing with one semi-local dealer because of the clap-trap he dished out concerning oil. When HD came out with there own brand of synth, he suddenly saw the light, and acted as if it was the Second Coming. He also priced it a $9/qt. Stupid is as stupid does. As far as I'm concerned he is "less than honorable".

I've been using Mobil 1 auto oil in my engine for over 60k miles. When I pulled the top end off to replace the dreaded Evo base gaskets, the hone marks were still visible on the cylinder walls.

I've been using the same Mobil 1 auto oil in my primary for over a year, and have had no clutch slippage.

I use Castrol synthetic 75w-90 gear oil in my tranny. It shifts as smoothly now as it did when I bought the bike. I won't use the 15 or 20w-50 oil in the tranny because of several mechs I respect telling of problems they saw. Possibly coincidental, but good enough for me at this time. Several riders I know shifted back to gear oil because their trannies started shifting rougher. Might've been the power of suggestion, though.

I saw the results of an independent analysis of Mobil 1 15w-50 car vs Mobil 1 20w-50 V-Twin and there was virtually no difference, and especially not enough to justify an almost doubling in price. The friction modifier issue has been raised by several journalists, as well as the oil manufacturers. But the journalists who've raised the issue got their info from the oil folks. Until I can read an independent study of the issue I can definitely understand someone's hesitance in using the auto oil around a clutch. But as I said, I've been using it for over a year with no problems, so I'm going to continue. Maybe I'll be the forum's guinea pig on the subject. <G>

 

pococj is right, you can run the 15-w50 redcap Mobil1 oil's,alot of rider's do with no problem. I personally run the V-twin oil which is alot higher[sm=boohoo.gif],but that's ok since the bike cost so darn much. Just to show that some dealer's aren't bigot's,my dealer let me bring my on oil(Mobil1) to the first 1000 mile change with no problem what so ever,he also stated I could run what brand I wanted wiyhout voiding the warranty,as long as it's not some junk oil.