Oh no on oil types

Some Ozark shops have containers of used engine oil they drip into wood stoves to recycle for warmth.
This is a geologic vs synthetic oil thread to ponder.

http://www.cedengineering.com/upload/Ba ... ations.pdf

Lubrication
Highly refined mineral oils are among the best lubricants for ball bearings. Synthetics have been developed that are good but some do not form elastohydrodynamic (EHD) films as well as mineral oils. EHD refers to what happens to the oil between the ball and pathway when the bearing is rotating. Research has shown that a film of oil builds up and, under some circumstances, becomes thick enough to completely separate the balls from the pathways. Thicker films result in longer than what the life equation predicts while films that are too thin result in excessive metal-to-metal contact and shorter lives than what the equation predicts. Empirical equations have been developed based on laboratory testing of the various factors that affect oil film development.

T is a measure of oil film thickness. Figure 20 shows that values of T below 1.5 can expect marginal lubrication for bearings while values of T above 1.5 can expect good lubrication. B is a bearing factor which takes into account physical characteristics of bearings that influence oil film thickness. B is largely dependent on bearing size with larger diameter bearings developing thicker oil films. The kind of bearing used has a smaller effect with radial and angular contact ball bearings falling into the middle of the category. O is an oil factor which is influenced primarily on oil viscosity at bearing operating temperature. The type of oil used has a smaller effect with naphthenic being the best, paraffin lying in the middle, and synthetic being the worst. S is a speed factor which shows that higher speeds generate thicker oil films because of the wedging effect of oil into the contact zone. L is a load factor which demonstrates that higher loads result in thinner films. Graphs of all the above factors have been developed which makes it easy to calculate oil film thickness and its affect on bearing life. [lube graph about 3/4 way down article]

bearing roller "skidding" is a long suffering topic, greased bearings, specifically recirculating balls used in linear motion guides will skid when molebdynem grease is mistakenly used. Once scars from skidding are formed, they feed on themselves.

Yes, I agree. Oil is good and we should all use some.

LOL, love the "Aw Jeez" pic!

Flashes me back to Bob Cummings greaser hair doo era TV actor.


This article covers some syn oil vs crude oil issues I didn't know until now. Yo'll have to care enough to find em in here but here's a quote that is reassuring.


http://www.post610.org/truth_about_motorcycle_oils.htm

BEARING SLIPPAGE

Talk to many motorcycle manufacturers/dealers (especially HD), and you'll find that they might tell you to avoid synthetics in your bike. That trend is slowly changing, but I wouldn't be surprised if you run across someone who tries to tell you that synthetics will ruin your bike. Most of them refer to bearing slippage. They say that synthetic oils are "too slippery" to maintain enough friction for bearings to roll as they are supposed to. As a result, the say that using synthetic oil will cause your bearings to "slip" instead. Of course, if that were to happen, flat spots would occur on bearings. That is a bunch of nonsense. Of all the motorcycle mechanics I've ever spoken with, I've never had one of them say that they've seen any flat spots on bearings in bikes that used synthetic oil. It just doesn't happen.

If synthetic oils were worse for rolling element bearings than petroleum oils, we wouldn't be using them in jet turbine engines, Formula One race cars, motogp bikes, etc. Just more internet nonsense.

Ken

For decades now I have heard all the stories of how synthetic oil would cause oil leaks on older engines.

When asked why, people would say because synthetics are so "slippery" they are able to make their way out between gasket surfaces easier than non synthetics.

Thinking this made sense, I only used non synthetic engine oil in my Norton motor.

Then many years ago I tried some Mobil 15-50, did not leak out anywhere, certainly not more than non synthetics.

I frequent one of the vintage Mercedes Benz sites and own a few of them. I mentioned that I used nothing but Rotella synthetic oil in my old cars. I was amazed buy the reaction I got from the vintage owners. All about how synthetic oil would leak out and destroy the rope rear main seal and cause all kinds of other problems. Good thing nobody told me that 25 years ago or I may have missed out on the advantages of synthetic. And my 67- 230 still doesn't leak a drop. Jim

Isn't it true that the only thing that makes synthetics unique is the uniformity of the chain length of each individual molecule?

rpatton said:

Isn't it true that the only thing that makes synthetics unique is the uniformity of the chain length of each individual molecule?

Click to expand...

That is about it. Both are made from "dead dinosaurs". In fact the word synthetic on the bottle does not even mean it is synthesized from natural gas anymore. It just means it is high grade oil with controlled molecule size.

Some of the oil suppliers who supposedly use only "synthesized molecule" oil advertise as being "pure synthetic" but that is not an official denotation. I have been told it is difficult for a lab to tell whether a synthetic oil was made from hydro-cracked crude or synthesized natural gas. Jim

This article goes nto the molecular size issues of crude vs syn oil.
http://www.post610.org/truth_about_motorcycle_oils.htm

Basically says crude oil various size hydrocarbon chains mean the longer ones get pressed to walls of passages and tend to adhere to surfaces, which then don't allow as much heat transfer to flowing oil and cook to carbon coke and corrosive etching acids easier. Also goes on to say the crude oil's various length chains tend to tangle with each other more than more similar sized chains of better refined and better base stock synth. oil, so more internal friction and heat developed than synthetic.

After dozen yr now learning curve balls of Commando operation and various oils I've come to conclusion the type of oil ain't as important as how Cdo's areoperated, ie: don't start on dry cams, let it wet sump and don't lidle slow to warm up, keep it in 2000's+ cam oil surf zone and don't start up and shut down until hot enough the thin ZADP layer that gets wiped off on 1st few turns is reformed again. Much as Norton can easy lug along like a short shifting Harley its bad juju for oil surfing engine parts and gearbox sleeve bushes.


I was greatly surprised with Combat Trixie run exclusively on crude grade Rotella 15/40 hi detergent diesel oil to hardly see any dusting on sump magnet and better finish-burnish on cam lobes and lifters, even after air filter boots cracked and grit ate off ring edges and doubled ring gap for bad smoking blow by. Ms Peel which had expensive hi end parts and cryogenic tempering and dry friction coating everywhere and run almost exclusively on Mobile One synt. 20/50 - but idled long for warm ups and lugged along easily carefully miles at a time d/t THE Gravel crash and fear lesions and oil changed @ 1000 mile intervals, showed a finger nail worth of ferric dust on sump magnets each time checked and lifters and cam scored and worn though surfaces.

My basic mood on this oil subject is intelligent pilot operation makes more difference than the amount spent on oil quality and quantity. Combine fast enough operation with good oil seems to give best life extension.