Oil Viscosity? What's Best

[webebob]

Geez I get confused so easily.

I watched GM explain how through wonderful new machining and honing technology, they are now producing "no break-in" engines. They claimed it was an expensive process, but the limited number of engines they do it to can use synthetics from the get go. But after reading this 4 page explaination of oil theory, I see it was really possible all along. No special machining required. GM sure waisted their money They also claimed their bores are good for 300,000 miles with the new process.

I've yet to hear a synthetic zealot explain why when Mobil introduced their synthetics to the aviation community a few years back, they had to pull it off the shelf after having to buy over a thousand of their customers engines. They re-released the oil with the addition of "friction modifiers, anti-scuffing agents and anti-corrosive agents". Sounds like they added good old fashion motor oil to the mix to me.

I've got nearly a thousand track miles on my cobra. I've always run regular oil. Last year I ran Mobil One at the track. I came home and had to replace engine bearings. The oil pick-up in a wet sytem will always get a good gulp of air on a road coarse and I found synthetic oil to provide no benifit from this extreme but common condition. I ran Putnam Park yesterday with regular oil and came home with the same oil pressure I left with.

Seems to me, it is more important that you have oil, than what kind.

Maybe someone can explain why I am so confused.
Bob

[webebob]

Ya, I remember this lawsuit. Another reason for the average joe to be wary of oil claims. I can't believe they won that one.

Bob

Originally posted by Lubrecon


Ok guys, you think I stirred the pot earlier, how about this, Castrol Syntec is not a synthetic, it's not even a synthetized hydrocarbon(PAO), like Mobil 1. Guess what it is and you will get the straight skinny on why they can call it a synthetic when it is not. BinB need not enter this contest without some proof...of..of..of something! [/b]

[mr0077]

Guys, I remember reading about the lawsuit; wasn't there a quality control problem that resulted in some sand or silica particles getting in the oil? General Aviation guys are used to 1950's (or older) technology, and a lot of "old husband's tales" (as I prefer to call them) abound, some VERY good, some...well, interesting. However, the contaminated oil did a number on both the engines and the "never again" attitude of a lot of GA A&P mechanics toward synthetic oils.
Webebob, I seem to remember reading something about the improved machining and ring material, and "no-breakin" motors too.
Good thread here.

[Mr.Fixit]

I thought the "no break in" rings were different only because they already have the bevel on the backside, no waiting for it to bevel itself.

[Lubrecon]

Webebob: I must have missed the story on Mobil having to buy 1,000 aviation engines because of them using a "synthetic". Were these jet engies or recips? General avaition or commercial? Would you point me to where I can get the skinny on this. The only synthetic that I know of that Mobil sells to the aviation inductry is Mobil Jet Oil II. It is a polyol ester, nothing like Mobil 1, that is a PAO. It has been around for many years and has been a standard for jet engines during that time. There are other companies that have jet engine oils also, and nothing but synthetics are used in jet engines that I am aware of.

Bob, you still didn't guess what Castrol Syntec is...come on, give it a try. Your getting warm with the lawsuit stuff though, but it wasn't a lawsuit.

Mr. Fixit: This is not a smart a__ question, but how can rings bevel themselves?

Jerry

[Bob In Ct]

Hey Guys:
I believe Mobil "builds" its Mobil1 from mostly ethylene (C2H4) molecules (a gas). Syntec, although a fine product, is still a refined lubricant. Castrol finds the molecules it wants in their crude oil and separates them out. What they are left with is what they called a "synthetic" lubricant. Many disagree, as I understand it the courts did not.

On mixing oils the best reason not to mix brands is the possibility of the additive packages not working well together. The hydrocarbon part is close to identical. The antifoam agents, and so forth may not get along well from brand to brand.

Bob

[niles]

For: Lubrecon and Bob Para.

I don't want to dip an oar into the wife tale contest; but both of you have forgot more than I ever knew about oil. Would you be kind enough to answer two questions?

1. What oil do you run in your hi-pro engine?
2. Whats your opinion of the accusump?

thanks

gn

[Satanpez]

I believe the Syncron is basically over-refined oil. Mobil sued them because of this, but it turned out Mobil was basically selling the same thing in Europe.

Supposedly they change the oil enough chemically in the process that it's not what they started with, hence "synthetic".

Not an expert obviously.

You can do a google search and find the exact info.

-steve in nj-

[Mr.Fixit]

Rings,
They start out with nice sharp corners and a rectangular cross section. After scrubbing up and down in a bore a bunch of times, the corner rounds off a bit. They do have a little bit of rocker action in the ring lands. Modern rings already have the bevel from the start.
That's the way it was explained to me, but go ahead and ask the pro's that make piston rings, I would be content to hear what they say happens to piston rings during "break in" from a more qualified source.

[Lubrecon]

Niles: I run Mobil 1 15W-50 in my 408 stroked Winsor. It is slightly on the heavy side viscosity wise, but the engine generates a lot of heat and I want the viscosity at the higher engine temps.

The accusump is a good addition, especially on the start up side. Pre-lubing any engine will significantly reduce start up wear and add to the engine life, regardless of the oil in use(ND excepted). There are other products that will pre-lube, but won't provide oil pressure if the oil pump were to loose suction from the oil sloshing in the pan. However, the pump products can be interconnected to your ignition so that you can't start the engine without a preset oil pressure being reached by the pump.

[Bob Parmenter]

Wow niles, nice set up questions.

As I often advocate, there are always variables that we fail to consider, so let me throw out some qualifiers as I answer your questions so that we can minimize the eeks

First, that forgetting thing gets easier with each passing year. I've gotten so good at it I sometimes I think I've forgotten more than I've ever learned!

Qualifier: I don't push my engines hard any more so there's no need to consider the abuse factor.

With our moderate climate and my car not running hot and hard (easy now!) I use 10w/30 dino juice of the latest/highest API quality grade available. If I lived in a hotter clime and genuinely pushed my car hard for prolonged periods, I'd go for a 20w/50.

I am purposely avoiding brand names because, quite frankly, I don't think it matters as much as most people, AS LONG AS IT IS A QUALITY BRAND THAT MEETS THE LATEST SPECS. Besides, in a world of Quaker State-Pennzoil, Exxon-Mobil, Chevron-Texaco, Union 76-Phillips66-Conoco, ad naseum, those brand loyalty lines blur more and more. I can't help but chuckle about some of the people I've had in classes over the years that swore by Pennzoil and just knew (because Uncle Ezra told them so) that that Quaker State stuff was junk. Wonder what they're thinkin' now?

And my not using synthetics isn't an unstated dislike or distrust of them, I just don't think that the conditions I operate in warrant their additional benefits. I don't keep vehicles long enough to gain the benefit, if any. I've had customers who follow first rate maintenance practices, get 2-300,000 miles of service on gasoline engines with the "old fashioned stuff". I've also seen users that can destroy a perfectly good engine with the same stuff. SERVICE FACTORS AND OPERATING CONDITIONS MATTER. I've never run across an engine failure that could conclusively be pinned on the lubricants fault. There has always been some other factor. Of course if brand loyalty were an issue I also always heard; "Well, that was never a problem for my previous oil".

Accusump? They really look neat!!
We could get into a long discussion about hydrodynamic lubrication. But not now. The theory of the Accusump premise is, well, accurate. It is true that most engine wear occurs at start up. (p.s. think about that in the context of the above discussion re. dino vs syn). If you accept that premise, then what's really important is how quickly the oil starts moving through the system. Now we're back to that pesky viscosity stuff again. Which could lead us to low temperature flow, high temperature........I digress. So, (QUALIFIER) in my opinion, if you use the correct viscosity (avoiding the "more is better" syndrome, or it's cousin, "bigger numbers is better".....................and here I am addressing a bunch of guys who have to have over 500 cubes and 600 hp in a 2300 pound car. Where's the L for my forehead?) then hydrodynamic flow works fine. Dam*, there I go, talking about that flow stuff again instead of pressure (bring in another L!) If you expect your engine to sit for prolonged periods without the crank rotating, or you insist on using too viscous of an oil, and you want to see if you can get 500,000 miles out of your engine, then the Accusump will do you some good. Otherwise, it really looks neat. And it gives you something cool to talk about when you're at a track event or a show. The last point is none too insignificant when dealing what obviously is an ego mobile. Lastly, if having one makes you more secure about the expenditure you've made on your engine, then "that's a good thing".

[mr0077]

Guys (Lubrecon and Bob P), the thing about the accusump and start-up wear...and this isn't a smart-assed question, just curious: Where does the "majority of wear at start-up" occur? As an engineer and auto enthusiast, I'm guessing it occurs at the rings, not the bearings...but has anyone actualy quantified where the wear occurs? Now, as I understand it, the accusump only oils the bearings and other areas that receive pressure lube, so does the accusump "really" help at start-up, if the primary wear points are at the rings and cylinder walls?

[paul cass]

ken
send me an email to fia28950@aol.com. i've got a question for you.
paul cass

[Mr.Fixit]

A few things I copied and pasted:

Red Line recommends breaking in an engine on straight viscosity oil.
Red Line does not recommend mixing race oil with regular oil.

Refining step 3: Add Detergents. Reacts with oxidized material. Helps keep piston rings clean (Rings are quite hot). Leaves an ash residue when combusted. Not used in airplane engine oils.
In an automobile engine, the piston speed (RPM) and therefore piston tempature changes greatly and quickly. The tempature differences allow the ash to break up into small deposits, and go into the exhaust or blow by the rings into the crankcase and lubricants.
In an airplane engine, the pistons are operating continuously at a single speed, and therefore do not go through heating and cooling cycles, so the ash deposits would not break up.
Generally, for automobile motor, lubricant is limited to 1% ash content. 2% ash is asking for trouble (although 2% may be okay for a diesel engine). Red Line Racing Oils are low detergent. Detergent is left out because ash can cause detonation.

[webebob]

Originally posted by Lubrecon
Webebob: I must have missed the story on Mobil having to buy 1,000 aviation engines because of them using a "synthetic". Were these jet engies or recips? General avaition or commercial? Would you point me to where I can get the skinny on this. The only synthetic that I know of that Mobil sells to the aviation inductry is Mobil Jet Oil II. It is a polyol ester, nothing like Mobil 1, that is a PAO. It has been around for many years and has been a standard for jet engines during that time. There are other companies that have jet engine oils also, and nothing but synthetics are used in jet engines that I am aware of.


Jerry

The damage was to piston engine aircraft.

The oil was Mobile AV-1, synthetic aviation oil.

The problem was worse in the larger 360+ cubic inch engines (hmmmm - cobra size engines.)
Mobil agreed damage to the top-end of the engine, including sludge buildup, piston ring malfunction and piston blow-by resulting in cylinder/piston damage and high oil consumption.
They denied it caused any of the FAA documented damage to cams, cranks, rods... that was considered overwelming by the FAA.

The FAA yanked Mobils permit to sell the stuff for gen aviation in May 1996. See FAA General Aviation Airworthiness Alert AC 43-16.

Of course there was a class action lawsuit. Mobil replaced users with continetal engines larger than 360 cubic inches.

The formula was later modified and re-released to the market. It does not appear to be having such troubles now.

Something like that.

Bob

[Lubrecon]

Ken: I don't know if I have ever seen the start up wear location quantified, but it may have been in some study. Certainly the rings are a wear area as they begin to move, and since they are splash lubricated, start up would be the worst time for wear. However, since start up is a no load condition, there would be less cylinder pressure trying to force the rings against the cylinder wall. However, the bearings, crankshaft, rod, and camshaft, are under higher loads than the rings and cylinder walls, and pressure lubricated, and those first few revolutions are without pressure and thus little or no oil flow. And, usually, the oil galleries empty back to the crankcase as the engine sits idle and must be filled on start up. Additionally, since the crankshaft bearings are normally hydrodynamically lubricated, the crank journals are just sitting on the bearings before the engine is started, and for the first few revolutions there is boundary lubrication with very little, or only a hint of oil available for lubrication. The journal must be lifted off the bearing with an oil wedge created by the rotation and the oil pressure. The same thing applies for the camshaft to a degree, less load though, but it is higher in the engine and it takes longer for the oil to get to this area of the engine. Also, the cam lobe-lifter is all sliding friction unless a roller lifter is utilized, and there is very little oil on the cam lobe at start up, but there is valve spring pressure as soon as the engine turns and even brfore depending on where the valve is in its lift.

You are right about the Accusump not providing lubrication to the rings, but it would allow the bearings to be pre-lubed and thus minimize start up wear in those areas. While you would not impact the ring start up wear, you would on the bearings, and since the bearings are a much softer material than the rings or the cylinders, I would surmise that the wear rate would be greater at start up on the bearings than on the rings.

That is my lubrication logic for the day.

Bob, your comments and thoughts are appreciated.

Jerry

[Mr.Fixit]

Sounds like what REDLINE described as to why they don't put detergents in their aviation oil. The stable rpm doesn't allow the ash to get broken up, so it stays at the rings. Just guessing

[Lubrecon]

Bob:

Went to the FAA site and searched for the May Alert AC 43-16. Could find nothing for May 1996, and nothing on Mobil and the oil problems your are talking about. Might you have the wrong Alert number? Also went to a Mobil Products book, and they have 3 synthetic oils offered to the aviation industry, all are for turbine, or jet engines. The recip engine oils are all mineral, called the Mobil Aero oils, Numbered Series and Banded Series. Two types, a straight mineral oil and an ashless dispersant oil. Both have military approval.

Are you sure the Mobil problem oil was a synthetic for aircraft recip engines?

Jerry

[Wayne Maybury]

Jerry
While your analysis on start up wear all makes sense, I have seen bearings, both main and rod, that have come out of well maintained engines that have been run many, many miles and therefore have had hundreds and hundreds (if not thousands) of cold starts on them. If the oil and filter have been changed regularly and replaced with good quality items and the engine has not been abused, those bearings look almost new, so start up wear on bearings cannot be too bad.

Do you ever rent cars? I do, often, at airports where the car jockeys drive me nuts. In the middle of the winter, they will fire up a cold engine, pop it in drive, and hammer the gas to the floor. Now we are talking about severe start up wear. I decided many years ago that I would never buy a used daily rental car.

I have a question for you. I have a new Explorer with a 4.6 L V-8. Ford recommends 5W20, year round. It just doesn't seem right to be running in the hot weather with it so I used Castol GTX 5W30 this summer but I will switch back to the 5W20 for the winter. Why would Ford recommend such a thin oil? Does it have to do with gas mileage?

By the way I run Castrol GTX 10W30 or 15W40 in my Cobra. The higher viscosity 15W40 gives me better hot oil pressure at lower revs in the hot weather. Both give about 55 to 60 lbs cold and 50+ lbs hot at highway speeds. Maximum oil temp that I have observed was 230 degrees, the engine temp was 195 or so at the time. Great thread, interesting stuff.

Wayne

[Lubrecon]

Wayne:

As you suspected, gas mileage is the reason for the 5W-20, year round. This helps out slightly with the frictional losses associated with the crank plowing through the oil in the crankcase and other frictional loses associated with oil viscosity. It is a result of the CAFE(Corporate Average Fuel Economy) requirements placed on the manufacturers by our bureaucrats in DC. The fuel benefit is not much, but everything helps when the heat is on.

5W-20 is ok for the winter, but I stay with 5W-30 year round in my regular cars. It's a good compromise for both summer and winter.

I too have seen bearings with 100,000+ miles look like new, but the type of driving and ambient conditions are a big factor along with oil and maintenance. What you want is quick flow to all parts of the engine, thinner oils do that, then you want the proper viscosity at operating temp. Without multi vis oils, that used to be a compromise, but no so today.

However, at risk of sounding like a broken record, PAO's have better flow characteristics(viscometrics) at low temps than do mineral oils, it's called borderline pumpability and viscosity index. PAO's simply have better numbers in these areas than Group II basestocks. Group III stocks approach the PAO's with respect to VI and other parameters, but still they are not as good, in these and other areas.

We are getting close to the Castrol Syntec debate.

Jerry