My understanding is that this is a true statement. This is a benefit because it adds additional protection against boundary lub failure. I believe that esters are bettter in this area than PAO's. Someone correct me if I'm wrong.
Castrol brags about "clinging" but Castrol brags about other things that most of us on here have found to be more "marketing" than actual facts.
Synthetic oils have been proven to flow better under most conditions and to have better resistance to most destructive conditions than petroleum oils, but as far as "cling-ability", by definition, that "flow-ability" is a direct contradiction.....
Synthetic oils will not be as "sticky" as oils that have more of the "viscosity improver" (polymers) added to them. If you want "sticky" oil, add some of the STP type additives, there is a NOTICEABLE difference when the VII is added, even in small amounts.
It's easy to check out, just pour some comparison oils in a glass jar, tilt them and watch the oil coat the glass and see how long it takes to drain back to original level...not very scientific, but it shows the difference nevertheless.
It's a good activity for those Saturday afternoons that the weather is perfect for staying outside, the smoker is going and the day is just one of those football days....
Unless the oil is magnetic, there should be no attraction to ferrous compounds, anything else would be just "sticky"...glass/metal..whatever.
The barrier lubes are like the cure on an iron skillet...works better when there is oil over it, but is better than raw iron for the short run.
I believe synthetic oils may be better than petroleum in certain conditions, but they are NOT miracles, they have limits just like anything else.
Try using a metal can instead of a jar, you'll still see a difference.
Full synthetics that contain esters do have a better "affinity" for clinging to metal parts.
Esters and sulphur-type chemicals (such as ZDDP and Moly DTC) both are polar in the sense they adhere to metal as well, but by different mechanisms. It has been shown that the combination of esters and moly provide good high temperature AW properties because they both have a high affinity to metals.
Sometimes surfactants are used to help bring the additives in the base oil to the metal if the oil does not contain esters.
On another thread I posted:
"An interesting SAE paper (951037) describes the process.
As a side topic, they also show that "organomolybdenum dithiocarbamates" are effective at improving fuel efficiency at high temperatures. "The effect of the type of FM on the fuel consumption was also studied in SAE 5W30 oils. The FM's evaluated included ester, organomolybdenum dithiocarbamate, and a mixture of these. The effects of the FM's were not significant at 66 C, whereas the use of FM's, in particular MoTDC, was beneficial at high temperatures..., where the boundary friction would play an important role."
This is one thing that has always confused me. When I used to tell people how synthetics were better because they clung to the metal longer after shutdown, they would then ask me how this is possible when synthetics are supposedly "more slippery" I never could quite figure out how both of those things could be true. Although I do doubt that synthetics are more slippery, I don't think they really are, which is why I wonder why car makers still say not to use synthetic until the engine is broken in. I can't see how a synthetic oil will possibly slow down the break in process. We have seen proof on here that conventional oils can show the same wear levels in used oil analysis as more expensive synthetics. The synthetics simply last longer that's all, and flow much better in cold weather.
Patman, I have a brocure from Exxon/Mobil for an industrial lubricant called "Synesstic". This product is a diester base stock. They say: "One key to film strength is the polar molecules of the Synnestic diester base stock. These molecules line up on metallic surfaces like the nap of a carpet, creating a strong lubricant film that helps prevent metal-to-metal contact."
They provide graphs where the Synnestic ISO 32 lubricant provides the same performance as an equivalent ISO 68 mineral base oil (same additive package). That article used to be here:
but they removed it . Let me know if you are interested, I can send you a copy.
- The use of synthetic esters : these molecules adhere to the metallic parts of the engine, thus reinforcing the resistance of the oil coating.-
It seems from reading there are two different bonds.Long chain non covalant vs Polar.
I recently read about a company working on a Mo that uses either less,different type or no sulphers used at all to attach Mo to metal engine parts for the future and GF4. Will try to find and post
Quaker State GRoup III synthetic clings to the insides of my engine like there's no tommorrow.
I popped open the oil filler cap and the stuff was everywhere (after 8 hours of sitting still).
With Group II+ dinos, the oil would just drain down. With the GRoup III there was a nice layer of film all over everything.
I think we are talking about two different levels or views of looking at oil.
One is the "Macroscopic" view where we visibly see oil cling to engine parts. This clinging is done naturally by synthetics or by other oils using "clinging" additives (tackifiers such as polyisobutylenes, and by surfactants such as you see in Schaefer's #132). This is done mainly to carry additives to the metal parts and "wet" them so the oil is not slung-off by inertial forces.
On the "Microscopic" level, esters have polar affinities in that they enter the metal with their molecules to form a thin surface layer of molecules. Then there are FM's and AW additives that
actually "coat" the metal with a series of layers of harder or softer metals in order to reduce
friction and wear.
Just because the oil coats the metal with a non-running additve does not necessarily mean that the oil is protecting the surface layers of the engine from wear; that's is a false perception.
Yeah, it just means the oil is there during a cold start which makes a big difference.
W/ dino 5W-30 my 4.6 was very sluggish during the first 2-3 miles in sub 40F weather.
W/ Group III 5W-30 it felt totally warmed up.
W/ Mobil 1 it felt the same as it did w/ group III.