That's a 500 level chemistry lesson. But in more simplistic terms the shape and consistency of the hydrocarbon. If you produce a lot quickly it's more difficult to control the outcome. Produce the same group slower in smaller batches, the outcome is more consistent. That's why Shell wants this GTL to work so badly. They can make a lot of GTL with more consistency, nearing PAO quality, much faster and in larger batches. It will have pack carrier drawbacks like PAOs but that's not a huge concern for them. Contamination control is more important than anyone realizes. And that's what's going to be the issues from hear on out. And base oils ability to carry a pack and the packs robustness and synergy will be the new focus. The large companies focus on base oil (Synthetics in general) and shear stability. If you run your engine and it fails on their oil, it will be dilution or contamination related. They don't have blame then. Smaller companies have the ability to match both the highest quality base oils (mineral and synthetic, which ever gives the most synergistic product with their chosen additive pack) and the highest quality add packs ( which cost more than the base oils do) to help contamination through better ring land sealing and placing the contamination into the full flow Filtration more effectively. Sent from my iPhone using Tapatalk
I've dealt with non Synthetics that cost 100 times that of a synthetic. Tribology is a very deep field. Sent from my iPhone using Tapatalk
Jim, the difficulty I'm having with some of what you are saying is that it doesn't seem to align with what I have seen as far as engines are concerned. As I mentioned, we did numerous teardowns with Mobil1 vs dino and, in every case, the dino oil showed more wear for the same load/time on the same bearing surfaces. Admittedly, the wear we are talking about is minimal in both cases but the difference was consistently measurable. Also, 30 wt Mobil One showed the same oil pressure/RPM as dino oil of the same viscosity. BUT this did not hold true over time. In fact, with dino oil you could watch the oil pressure at idle and know when it was time to change the oil because the pressure would be noticeably lower (though totally safe) as the oil aged. This did not happen with the Mobil 1. I still use that "method" to know when to change oil on a pair of Detroit Diesel marine engines. When the idle (550 RPM) oil pressure drops to the 25 PSI range the straight 40WT dino is due for a change. (That's not unsafe, anything down to 12 PSI at idle is OK per DD for the 8V71TI), engine wise) I have no knowledge of the subject whatsoever as far as anything to do with oil composition. All I am relaying is personal experience with engines over quite a long period of time. If Mobil One is not really "synthetic oil," I'll certainly take your word for that. But its performance was measurably better than, say, Valvoline, Castrol, Penzoil, Quaker State (don't get me started on that Cr@p)...the usual "conventional oil" suspects. Again, please remember I am talking about comparing Mobil One with the conventional oils of the time when M1 came out. I have not been involved in such engine testing since I retired about 10 years ago. SO none of what I'm saying is current based on my personal experience. But I still have folks in the performance engine building world many of whom have gone to 0W20 or 0W30 synthetics. Obviously, that depends on the clearances/cyl wall finish/piston ring type, etc. But with the tighter clearances, lower viscosity oil, the friction is reduced/power increased with no increase in engine wear. OTOH, as you pointed out, Top fuel teams, with their extremely loose clearances and impossibly high HP often use 70 wt oil. The viscosity needed for proper engine protection is totally about internal clearances/piston wall/ring compliance. 0W20 will provide sufficient pressure for long engine life with tight clearances. For an engine with looser clearances, 20W50 might be what is required. Some builders prefer looser clearances, others prefer tighter. We always preferred tighter and blueprinted engines to the minimum spec clearance in virtually all cases. FWIW - to relate to 3x8 motors - per the factory specs, the clearances allowed are rather wide which was surprising to me when I first got interested in a 328. I expected a lot more "precision" from Ferrari. But that wide range of "slop" makes it obvious why some 3x8 motors use a quart of oil or more in less than 1000 miles (which was within factory tolerances) and why others needed 3000 miles to do that.
Firstly, oil pressure and film strength aren't directly related. Hydrodynamic films on journal bearings is 1 to 6 microns. It's generally only through measuring HTHS that the difference is seen (so comparing oil pressure would really do the diffeeence in viscosity I'm speaking about any justice). There's not another direct test outside the relative correlation between viscosity @100 and 40 c. Which are the two points drawn VI to. Yes, increasing Vis increases oil pressure, but they are indirectly related. Viscosity should be chosen firstly by taking load and opposing bearing surface velocities into account. Increasing load without increasing velocity (increasing RPM, increasing journal diameter) or decreasing load through larger bearing size will require a higher viscosity. This is all done by the OEM. You cheat it by reducing your clearances. But 1-6 um is 1/5 of a thousandth, so unless your clearances are below .2 thousandths your viscosity is again only indirectly effected. There are engines that run those clearances, but the oil and the engine are warmed up prior to running, totally different conversation. You can also cheat this by ramping horse power up farther in the RPM. Thus reducing the load to velocity ratio by not increasing load until velocity is high enough to circumvent possible mixed and boundary film regimens. The real issue here is knowledge base. The United States falls way behind in tribology compared to most of Europe and Asia. The first US born engineering program that focuses on Tribology wasn't started until 4 years ago at Auburn. And I believe it's still the only one. One damn college in the entire country... getting a phd in chemistry with a tribo focus has been the only way anyone has gotten into this field until recently. Hopefully the future holds more promise. But, it makes me extremely valuable, so I suppose I'll keep taking advantage of the situation. Great discussion btw, thanks! Sent from my iPhone using Tapatalk
