Synthetic oil nonsense

[Jim]

There is a small leak in the rocker cover on my Sportster and the dealer said it's because I am using synthetic oil. I heard this from more than one Harley shop. They also said the engines are noisier with synthetics because they are so thin. What the heck started that tale? They are too thin and that is why it leaks.

So I am wondering if synthetics have a different surface tension or something that might have started this rumor.

I sure hope what they said is not true because I just bought a case of Redline 20W50 oil.

I am also doing a test on a piece of bare metal with Redline and conventional oil. The metal is out in the weather to see if there is a difference in how fast rust forms where there are a few drops of each type of oil.

 

[NHGUY]

I believe the leak theory was valid back in the 1980s,but with the seal swell additives that all oils have,leaks shouldnt start with one brand vs another.Maybe the additional cleaning that a synthetic oil can perform makes a bad situation worse? I have seen no leaks vs conventional in a 3.3 Dodge with 94K miles running PU.So,I guess an engine should be solid beforehand.If not,then the oil will get blamed.

 

[Quattro Pete]

I think this originated in the early days of synthetic where some of the synthetic bases/additives were incompatible with gaskets and would cause these gaskets to leak. I don't think that's still the case today.

"They are too thin" mantra is just pure ignorance, IMO.

 

[Roadkingnc]

The synthetic oil did not cause your oil leak, that is b/s.
Some engines will make more valve train noise with synthetic but it wont harm anything. My Harley to end is noisier with synthetic oil but I don't let it bother me.
It is still 20w50 right? It is no thinner than dino 20w50 but it pours better. I would find another dealer. They sell their own brand of synthetic oil, does it cause leaks because it is too thin? I would ask them.

 

[FowVay]

I believe that in the early stages of synthetic oil technology (true group 4 PAO) the polyalphaolefin would actually cause seal shrinkage and gasket hardening to the point that leaks would occur. Further testing showed that adding some form of ester to the PAO would counter the effects of seal shrinkage and make the product more resilient.

Fastforward to today and the term 'synthetic' has become a marketing term used by everyone. SAE groups I-III are all based on mineral oils of paraffinic and napthenic origin. The level of refinement gives us differing levels of viscosity index and sulfur content so there truly are three distinct levels of quality. However, they're still mineral oils derived from crude.

Seal and gasket leakage on modern engines using any manufacturer recommended fluid is far more likely due to a poor sealing surface, seal damage, or simply poor assembly practice. The fluid isn't really the problem. If a gasket seals then it seals. If it doesn't then it doesn't. Surface tension and capillary action of the oil won't vary enough among lubricating fluids to cause the amount of leaks blamed on the oil.

 

[Donald]

There were also cases of a "false seal" made up of crud in front of the normal seal. The "false seal" would prevent from oil getting to the normal seal and it dries out a bit but still no leak. You add synthetic and it cleans up the crud but now the dried seal leaks. At some point, the seals gets conditioned enough and the leak goes away.

 

[Robenstein]

You did not mention how old the bike was, but seems that some shops/mechanics like to blame something for the premature failure of a part other than a faulty part.

My friend just took his one year old softail into the dealership for the second time for serious transmission/primary work. They tried the "are you sure you are using the right oils" line on him also.

 

[Chris142]

Harleys were leaking

oil long before synthetic oils became popular.

 

[rraiderr]

Originally Posted By: Chris142
Harleys were leaking

oil long before synthetic oils became popular.


So painful but so true.

 

[Robenstein]

Originally Posted By: Chris142
Harleys were leaking

oil long before synthetic oils became popular.


As were lots of bikes, like my beloved British bikes. One good thing is the police could just follow the oil trail if someone stole your bike.

 

[Jim]

Thanks everyone for the replies. I am keeping the Redline in the bike. I bought a set of metal gaskets that are supposed to be better than the OEM ones. Changing them will be something to do when riding season is over.
The bike is a 2008 1200 Sportster Low with only 9800 miles on it.

I am still puzzled as to why there would be more noise with synthetics. I have heard this said quite often on the Harley forum. It's strange since the high temperature viscosity is better.

 

[ddrumman2004]

I have read that rocker cover leaks are quiet common on Sportsters. I have a 2000 XL 1200 with 15,720 miles that doesn't leak and I run synthetic oil in the engine.

I just bought a 2011 Heritage Softail from a dealer in Columbia TN and they told me full synthetics are to be used in all three holes. I suspect I could use something different in the tranny to help with shifting.

 

[rossn2]

Quote:
There is a small leak in the rocker cover on my Sportster and the dealer said it's because I am using synthetic oil. I heard this from more than one Harley shop.


What a load of phewy! If this were the case why do all the CVO bikes come with SE SYN3 oil from the factory and why to dealerships want to sell you the SYN 3 oil during your service on a bike?

 

[JR]

Had a sportster had tons os motor build-up. Syn or dino oil it would leak the same. I ran vr1 sae50wt. I switched to syn oil and it was noiser for some reason. I stayed with royal purple sae50wt, wasnt as bad. Helps in long run it did for my resale.

Ken

 

[fdcg27]

Would you rather that the shop tell you the truth?
The truth would be that the engine is built with obsolete gasket materials and may not have adequate and even clamping force on the rocker cover.
Synthetic oil doesn't cause leaks.
Bad gaskets and bad design cause leaks.

 

[Errtt]

One of the bikes is a 97 Sportster 1200 and I'm running Amsoil 20-50. No leaks..... yet.

I've heard synthetics clean and may reveal what was already a potential leak that was somewhat grummy layered with non-synthetic that wasn't revealing the leak...yet

 

[Clevy]

The evo engine was prone to leaking with synthetics,especially where the jugs meet the case at the bottom however the twin cam shouldn't no matter what oil was used.

 

[BusyLittleShop]

Both Dino and Synthetics Oils are made up of giant molecules
called polymers. Some are natural like mineral (Dino) oil,
others man-made like PAO. Dino and Synthetics polymers have
different shapes. Namely the molecules of mineral oil have a lot
of side branches, whereas the molecules of synthetic oil are
smoother and less "branchy." so technically speaking synthetics
flow easier than Dino but the polymers are not thinner or
thicker than Dino... however some still view synthetics with suspicion
and point to them as culprit to a whole host of problems...

 

[BusyLittleShop]

Originally Posted By: Jim


I sure hope what they said is not true because I just bought a case of Redline 20W50 oil.


Mercy HD is still recommending a 50wt??? Red Line 20W 50 has a start up viscosity of 139 and a running viscosity of 19...

 

[fpracha]

Originally Posted By: Jim

I am still puzzled as to why there would be more noise with synthetics. I have heard this said quite often on the Harley forum. It's strange since the high temperature viscosity is better.
It is due to the better flow properties of synthetics, while the normal engine noise is always the same, but dino oil dampens the sound a bit more than synthetics.