Synthetic Molocules Question

[hotroadking]

Newbee here, thanks for letting me join, now you have another HD rider in the mist of the great oil debates LOL

I constantly hear the talking down of Synthetics on HD's you'd have thought HD coming out with the product finally would put some of the myths to rest. However I've heard a new one.

One guy is reporting on boards that the molocules of synthetic are smaller than the molocules of dyno oil, and that's what causes synthetic oil to leak out of the motors. He's making statements that an oil engineer has told him this, and, that if you run synthetic as your motor ages you will develop leaks of course you have to get over 50K on the motor for it to happen.

I thought that leaks in older motors came from synthetic oil acutally not having the seal softeners that dyno oil has in the mix that causes seals to expand, thus filling in areas that dyno oil would get through if the seals/gaskets were of normal properties and not swollen to fill the void.


Any one wish to debunk or confirm this it would be appreciated, love to get some authoritative information thankns.

 

[doyall]

to the board hrk. Always good to have riders of all stripes aboard.

This topic gets (dis)cussed quite often in the Car and Truck Gas Engine Oil section. Here are some of the ones directly on point:

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=003808#000000

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=001455#000000

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=001432#000003

If you do a search you should be able to find enough to keep you busy reading for a while. In short, if you don't already have a leak, syn oil isn't going to cause one.

 

[msparks]

quote:

---

Originally posted by hotroadking:
Newbee here, thanks for letting me join,

One guy is reporting on boards that the molocules of synthetic are smaller than the molocules of dyno oil, and that's what causes synthetic oil to leak out of the motors. He's making statements that an oil engineer has told him this, and, that if you run synthetic as your motor ages you will develop leaks of course you have to get over 50K on the motor for it to happen.

I thought that leaks in older motors came from synthetic oil acutally not having the seal softeners that dyno oil has in the mix that causes seals to expand, thus filling in areas that dyno oil would get through if the seals/gaskets were of normal properties and not swollen to fill the void.


Any one wish to debunk or confirm this it would be appreciated, love to get some authoritative information thankns.

---

First off

There are 2 reasons that syntnetics could leak out of an engine. First one is that the base oil of the synthetic could be incompatible with the gasket/seal material that the engine uses. This is less common now a than in the past, since most synthetics use a standard base oil blend and most engines also use materials that are compatible with the synthetics.

The other reason, is that on older engines that have run Dino for several years, Varnish and sludge will build up on the inside of the engine. When this coating happens the seals and gaskets get no lubrication, therefore they shrink and dry out, sometimes cracking. But since the sludge is coating this it will not leak. When a person switches over to a synthetic, the natural solvency of the base oil will tend to clean the sludge and varnish away. When this happens the oil will then leak past the gaskets and seals. In some cases over time the seal swell characteristics can stop those leaks but it usually takes many miles.

If you go to the Auto-RX site you will read about the seal cleaning and rejuvination of certain organic products. The auto-rx has the same natual cleaning power that some synthetics do, only a lot stronger and faster.

This is the reason I usually have the person do a full Auto-RX treatment before switching to Amsoil. Usually 2 are needed for the engines that I see on a regular basis. Anymore I rarely see any problems with leaks especially after the Auto-RX.

 

[msparks]

quote:

---

Originally posted by hotroadking:

One guy is reporting on boards that the molocules of synthetic are smaller than the molocules of dyno oil, and that's what causes synthetic oil to leak out of the motors. He's making statements that an oil engineer has told him this, and, that if you run synthetic as your motor ages you will develop leaks of course you have to get over 50K on the motor for it to happen.

---

Oh and to debunk your friends statement. The molucules of synthetics are uniform in size. Molocules are not too short and not to long. Also they are double and triple bonded which makes them less resistant to shearing.

A conventional based oil will have long, short and in between sized molocules. Some will be much smaller than a synthetic base. What happens is that when the oil gets hot, these short molocule changes evaporate and form varnish, the long chains get sheared and form sludge.

A synthetic base oil should have uniform molocule sizes, which is the reason it's more resistant to the effects of extreme hot and cold.

 

[Arved]

quote:

---

Originally posted by hotroadking:
...if you run synthetic as your motor ages you will develop leaks of course you have to get over 50K on the motor for it to happen.

---

50K miles? That would be about 23 years of normal use by the average Harley RUB, right?

I've learned that discussing oil is a lot like discussing religion or politics. It's best not to disturb the zealots. When they're willing to calm down and discuss the facts, most can learn pretty quickly. A few poor souls are so brain-damaged that it's truely futile.

Oil Engineer? What school gives out degrees in Oil Engineering? There are tribologists in the Chemical Engineering field, but I don't think you can get a degree, let alone a PE license, in "Oil Engineering."

GIGO - Garbage in, garbage out.

- Arved

 

[MolaKule]

No such thing as Oil Engineer. You can get a degree in Petroleum Geology, Petroleum Chemistry, Organic Chemistry, Physical Chemistry, etc. Most higher degreed physicists, mechanical engineers, and chemists may work as tribologists and lubrication engineers/formulators.

Synthetic molecules have a tougher structure with stronger molecular bonds which is why they resist heat and oxidation better than dinos.

Another reason why they are more thermally and oxidatively stable is that the molecular sizes are more consistent, that is, they contain a narrow spectrum of hydrocarbons, whereas the dinos contain a large mix of high and low molecular weight hydrocarbons.

You have to actually add synthetic esters to a PAO based oil to get the seals to swell.

[ October 29, 2003, 11:05 AM: Message edited by: MolaKule ]

 

[Mike_dup1]

It this the guy?

[ October 29, 2003, 01:09 PM: Message edited by: Mike ]

 

[MolaKule]

That's my Brother!

 

[hotroadking]

Thanks for the replies yeah might take the average RUB a few years to get to 50K but he'll spend several hundred on fresh synthetic to protect the investment LOL

It is amazing the closed minds to the synthetic, I imagine it goes back to the first years where people had issues with bikes and put in synthetic only to find they had leaks and other problems, easy to blame it on the oil.

Even know a wrench that blamed a cam bearing failure on the synthetic mostly to cover a botched installation (IMHO) of the cam but we don't want to get into bearing loads do we?