Technical Switching grades and types of engine oil and its affects on engine noise, exhaust etc.

What weight oil to use is also based on the clearances , (crank /rod )From new to over time wear pluse rings to cylinder to bore , For most of us it's going to be trial and error & $$.
We do not have the resources to know for sure what is the best for Your particular motor ,
All motorsports /racing use different weight oil's and formulas , stick with brands that are Good oils , Rotella ,Valvoline race VR1 ,Lucas Breakin , these are Good oils with zink .
Good Quality oil filters & that start aNother debate, different microns for different weight oils , ALL SO just because you see brand of oil advertised on professional cars DOES NOT mean they use that brand oil !!!! It is only marketing / advertisement !!!!

 

I'll buy that the first number is the cold-flow viscosity, after all, that's one of the reasons why these oils exist; to reduce cold-start oil starvation. The faster the oil flows to everywhere it needs to go, the less wear you'll have. But claiming that the oil viscosity increases (if it's not 'thickening', what is it doing?) to match the 'straight weight' viscosity of the second number at 100C can be easily demonstrated as false. Put 10W-40 in your motor, run it up to full operating temp, then measure the amount of time it takes to drain when you pull the drain plug. Repeat with straight-weight 40. I'll guarantee the 10W-40 will drain faster... much faster. A drain plug is an 'orifice' too.

 

Steve, the oil viscosity doesn't increase, period. What it doesn't do is DECREASE as rapidly as the temperature increases, so it maintains it's viscosity better. I.e. it has a has a higher "Viscosity Index" (VI). At operating temp a multi-viscosity oil is the same viscosity as a straight grade oil, in fact it can be even higher, depending on the oils compared. I'll try to find or make a graphic to illustrate.

 

Here is a simplified explanation I found. It shows how a mulit-grade maintains it's viscosity better that a straight grade. Also note that at temps above 100C the multi-grade is actually higher viscosity than the straight grade.

 

Thank you, Blues4U

I have just pulled a 248 straight eight that I have put 10,000+ miles on since rebuilding. I have run Rotella T 15W/40 the entire time. Pan has not been pulled yet, but it will be since I screwed the gasket somehow. THE TOP OF THE HEAD AND ROCKER ASSEMBLY ARE AS CLEAN AS THE DAY I BOLTED IT TOGETHER. The "hopped up" 263 replacing it will use the same oil.

Ben

 

Blues4U

Thanks for the explanation and advise on the type of oil to run in our old clunkers. Invaluable to have advise from someone who knows what they are talking about, not just a back yard hack like me or someone with a product to sell.

Moderators, this might be a good post to have in the TECH section. It would benefit everyone on here.

Canuck

 

The chart notwithstanding, I'll still insist that a multigrade won't have the same viscosity as the 'equivalent' straight grade at operating temp. Again, the 'drain test' will quickly show the difference. If you can explain that, I might buy into the rest. And this has consequences in the real world too; I can give at least two examples. One, air-cooled motors. VW specifically warned against using 10W-30 or 10W-40 in their flat fours as the lower viscosity oil didn't 'cling' to the cylinders well enough and piston/cylinder wall scuffing would occur, sometimes to the point of engine failure. I've personally seen the same problem in air-cooled motorcycles, Harleys in particular. The Harley racers almost all use straight 40W or higher for this reason. Two, the 440-powered Dodge/Plymouth highway pursuit cars of the 70s were required by Chrysler to use at least a 20W-40 oil or they wouldn't warrantee them. And if you put 10W-40 in them, oil consumption went up sharply. According to you, these oils 'perform' the same as their higher-viscosity brothers, but that doesn't always prove out in the real world.

And many older motors weren't designed for multigrade; I had a 223 Ford six that had been rebuilt and the PO was using 10W-40 in it. It leaked everywhere and was very noisy on start-up and somewhat noisy while running. A switch to straight 30W and all those issues disappeared.

 

Thank you very much, not boring at all - best info I've read in a long time!

I' ve been using straight grade Castrol GP 50 SAE 50 (sold as "summer" oil for pre 1960 engines here in Europe) in my mildly tuned Merc flathead because everybody and his brother has told me this is the best and only oil for my engine. It's not cheap and I have to buy it online.

It almost feels like a sacrilege if I'd change to Diesel oil now....

 

showing these out takes just to try and figure out what a professional says, compared to others that have slightly differing ideas. know that it is not a perfect world when it comes to motors - look at all of the testing/changes that race teams do.

 

So now you're moving the goal posts, huh? First it was that multi-grade oils didn't increase in viscosity (though I never said they did), now it's that multi-grade oils are not good for all engines. That's 2 different arguments.

Keep in mind that technology keeps moving forward, and so do API service classifications and the performance requirements. Not all Viscosity Index Improvers are created equal, so years ago some oil blenders used cheep polymers with poor shear stability, which would shear in use. That was one of the differentiaters between oil brands, some used better polymers than others (think about one lube company that advertised how it's oil resisted "Viscosity breakdown"). Well, time marches on, and so does technology, and VII polymers have gotten pretty damn good. And API requirements have slowly increased the demand for improved shear stability, so with today's oil, in order to achieve API licensing all oils must pass a test (Kurt Orbhan Shear Stability Test) showing that their oil doesn't shear out of grade in use.

But all that is pretty much moot at this point, you cannot buy a straight grade oil blended to modern performance specs any way, so what's the argument? Multi-grade oils perform far, far better in many ways vs old straight grade oils, beyond the viscosity aspect. The anti-wear performance, anti-oxidation, the sludge and deposit protection, seal compatibility, etc, in every way. I really don't know what the discussion is about at this point. Are you recommending people go back to straight grade oils?

 

As a chemist I beg to differ. A multi weight oil additive package contains a plastic polymer that
resembles a cork srew. Under heat it elongates and expands ( thickens ) so that at operating temp
the oil has the viscosity of the higher number. Now here is where things get interesting. You are at the mercy of the manufacturer as to the quality ( cost ) of the additives he puts in the oil. Cheap additives break down and the lubricating
properties of the oil deteriorate. When that happens you have acceleated wear in your engine.
If you have a nice tight non leaking engine use a quality synthetic ( Di-Ester base ) with an etended
oil drain interval. You will have a better running longer lasting engine for the same or less money
spent on lubrication.

 

Cool story, bro, but it does not explain how an oil has the cold flow viscosity of zero.

Or, for that matter, if an oil has no viscosity when it is cold, how it actually lubricates, or maintains pressure.

 

Nope, just trying to get a straightforward answer to a question...

So let's ignore the 'thickening' thing and just address the viscosities at 100C temps. You claim (and illustrate in your chart) that 10W-40 and straight 40 have the same viscosity at 100C. So if that's the case, draining the same amount of oil from identical engines at the same fully-warmed-up oil operating temp would mean that both would drain in the same amount of time. The 'orifice' (the drain hole) is the same in each case, and you defined viscosity as:
'Viscosity at 100C is determined by measuring the time it takes oil to flow through an orifice and over a measured distance' (direct quote from your first post to this thread).
So we have the orifice and the distance (how far to the drain pan). Yet they don't drain the same; 10W-40 will drain much faster. Hell, there's a noticeable difference between 10W-40 and 20W-40, with the 20W being slower. Please explain why this happens if viscosities are the same. Simple question, should have a simple answer...

As to the statement that 'multigrade oils are not good for all engines', that's not a different issue, it's a related issue. You go on to talk about how much oils have improved over the years (and I don't disagree with that, they have) but seem to miss the point that as oils have improved, it's primarily been in response to engineering changes to the lubricated parts as much as general improvements. Name me one major oil manufacturer who tests for backwards compatibility of their oil for use in 50+ year old designs. You have some small 'niche' players who claim to do so, but no majors that I'm aware of. While I talked about specific instances where multigrade oil is a bad choice (or 10W-40 instead of 20W-40), I'm not recommending that all owners of vintage engines switch to straight-grade oils, merely pointing out that not all will do well with a 5W, 10W, or 15W multigrade. Some will need a higher viscosity, either a 20W-base multigrade or a thicker straight grade. I know my air-cooled motorcycles all have recommendations of a minimum of 20W-40 for any ambient temps above 42F. Truthfully, any vintage motor I owned would get that as the lowest considered viscosity unless I planned to run it in below-freezing weather. Never any 15W or 10W based multigrades, but that call is up to the individual owner and/or the engine builder.

 

That's a good point you raise here. I think I have heard and read a thousand times that new oils are not compatible with old engines for different reasons: 1. New oils destroy sealing rings, cork or paper sealings,.... of old engines. 2. Lubrication systems of old engines are not working properly with new oils.

Is that another urban legend?

 

It is not that the new oils destroy seals - it is that the seals in an old engine have lost their elasticity, dried out and have been coated with varnish from deteriorating oils over the years. The new oils with suerior detergent additives dissolve that varnish that was pluging the gaps and now you have a leak.

 

Thanks for explaining. That means that a newly overhauled vintage engine (new seals et al) can be treated like a new engine and driven with modern oil.

 

I'm that guy, and I disagree with your second statement, in fact, the majority of non-hambers I know are going to these cams, for a given duration at 050 they idle better and make more bottom end and mid range torque than cams with lazier ramps.
Oil is your territory, the other stuff you are on my turf...
I have been using Brad Penn mineral oil, but I think I am going to make the switch to VR1, as its cheaper and easier to get. I am afraid my wife might leave if I DONT change oil, she found a receipt to the last $100 oil change!
They keep tweaking the zinc level in the Rotella, I don't want to have a cam failure because they have lowered it again and I didn't hear about it.

 

well my buddy called the engine builder he is away til next week. local shops only stock the Valvoline Vr1 in 10W30 but he really thinks the 20W50 might be his best bet since he has been using the Rotella 15w40 for the past few years. car is gonna sit this weekend until he decides as the local store wont order the 20W50 without prepay for 2 cases of it.

 

this has been stated in other threads here on this topic - Rotella today is not the same Rotella as in years past - lower Zinc, etc

 

This is in agreement with Blues4U's comment,

"Now, with the reduced levels of SA, ZDDP levels have had to come down, but they are still well above 1000 ppm, I typically see zinc levels of around 1200 - 1300 ppm in most HD diesel engine oils. And, along with the zinc I also see a growing trend toward increased levels of boron and also moly, which both add to the anti-wear properties of the oil."

Better than no Zinc.

Canuck

 

About the statement ,I do know i!!
If you put modern gear lube's in manual transmissions & rear of the past ,the modern gear lube, what it's made of will attack & eat the bronz.
Also if the new stuff is so much better why are we having so many problems ,
New formulated gas eat's aluminum , New vehicles do not have grease fittings ,""balljoints,""
Tires dry rot blowout ,new tires never been on a car ,never in sunlight dry rotted !!!

 

Rotella still has relatively high levels of zinc, that's not the point. The point is that the zinc level has been moved lower 3 times that I know of over the last 5 years, and if they continue this trend, at some point the zinc level will be too low to support flat tappet cams. I don't want to be one of the guys that finds out they have crossed that threshold by having a cam failure that fills my engine with cast iron particles.

 

Some people much smarter than me that are in the lube business as well as some of the best engine builders out there would question this statement. I'm not going to take a side, but the trend is AWAY from molybdenum disulfide based assembly lubes.
http://speedtalk.com/forum/viewtopic.php?f=1&t=5990&start=30

 

As best as I can recall, years ago in auto tech classes multi-grade oils were described like this. Assuming a 10w30 oil, it was explained that at a given cold temperature it was never thicker than a straight 10w oil at the same temperature. And at higher operating temps it was never thinner than a straight 30w oil at the same temperature.

Now I don't understand the chemistry or magic that makes this happen, but that doesn't mean that it doesn't work that way.

 

That's what Blues4U was trying to sell, and it's just not true. Notice I've gotten no answer from him for the question I posed. And it can be demonstrated false in yet another way.

Originally designed to improve cold-start oiling (10W oil will flow faster/easier than 20W or 30W), multigrades had
an additional side benefit that was mostly ignored at the time; improved fuel economy. The thinner oil uses less power to be pumped, so a small mileage increase could be seen. This has been carried forward, and with the current emphasis on fuel economy, you'll now find multigrades as thin as 0W-30. So think about it; if 10W-30 or 0W-30 have the same viscosity at operating temperature as straight 30W, where's your fuel savings? They would hardly have bothered developing a 0W-30 oil if the only fuel savings to be gained are at start-up. They start out thinner, and stay thinner than the 'equivalent' straight grade oil. Try draining some 0W-30 and then tell me it drains the same as 30W...

Now, for pressurized lubricated parts, all this probably doesn't make that much difference (although if you get into the really thin oils it may). But where it can make a difference is the parts that are splash-oiled; things like cylinder walls and pistons, camshafts and lifters, valve train, timing chains, and various other parts depending on the engine. Thinner oil means a thinner oil film, and if the motor was designed for a thicker oil film, noise and inadequate lubrication may result. You can see much the same thing in modern manual transmissions; new ones use ATF rather than gear lube (again for fuel savings, and are designed for it), would you use ATF in your vintage transmission?

 

Crazy steve... your crazy dude! But your totally right about this. Drain it and see for yourself.
I can hear it from all the chemists and other learned guys in the oil industry but if they don't work for a specific oil company than they don't get the secrets. And the secrets about oils in our cars are only for them. Don't mean to be confusing here but i don't believe people who work in the industry... I believe what i see that actually works in my old motorcycle and my old cars...
If my bike or car made noises that wouldnt go away after an oil change i would change the oil until they went away.
Falcon george is on target also imo.
The question i have though is about different rpms and oils. Do you hear the noise after changing the oil at low rpms AND high rpms or just high rpms? Or just low? (55thunderboy) I would go back to the oil that you didnt get any noise at all in any rpms. (and that oil would be PENZOIL!!!) Hahaha. My favorite for no good reason since i was a kid. I liked loud yellow cars

 

Actually there are different types of polymers used, you described a very common type, but there are also "star" polymers with multiple arms radiating out from the center. The star polymers are much more resistant to shear forces. I have also heard of micelle type viscosity modifiers which reassemble themselves after being sheared, resulting in an oil with virtually no permanent viscosity loss. There are of course price constraints, so a blender must balance performance with cost, but as I posted above, current API specifications require minimum shear stability, so even the cheapest products, if they carry API license, have met the minimum standard.

Here's an easy to read article on viscosity modifiers, that discusses different types. http://www.infineuminsight.com/insight/aug-2015/next-generation-viscosity-modifiers

Here's a little more scholarly article on the technology for those that really want to get into it. There's a lot more info out there if you google it:
http://nopr.niscair.res.in/bitstream/123456789/30861/1/IJCT 5(5) 309-314.pdf

Re diester based engine oils, could be very could performing oils, with very low tendency toward varnish formation and deposits, but will also be very expensive, and hard to come by. Diesters are most commonly used for recipricating compressor oils, for their low varnish forming characteristics. Jet engine lubes are commonly made using diester base stocks, for the same reasons. I believe Redline may use diester base stocks for their engine oils. Note there are some concerns with diesters, notably they can cause seal swelling, so that needs to be controlled, and they can damage painted surfaces.

 

Well, if you read what I wrote about Viscosity Index (VI), it explains that not all oils have the same characteristics regarding how the viscosity changes relative to temperature. Some oils have a great rate of change relative to temperature, some do not. As an example, think of the can of Crisco shortening you may have in a kitchen cupboard. At room temperature it is very thick, doesn't flow at all, but put it in a frying pan on the stove and as it warms up it turns to a liquid and flows readily. That's an example of very low VI. Now think about a synthetic motor oil that you could put a container of it into your freezer and let it sit over night, then in the morning pour it out next to a container of the same oil at room temp, and you'd see very little difference, they both would flow at about the same rate. That's an example of a very high VI. So, to take this back around to your question, a 0W grade oil doesn't increase as much when it gets cold, it's viscosity remains able to flow. a 5W or a 10W oil will have a much lower VI and the viscosity will increase much more when cold. That's the difference. I believe you mentioned 0W30, right? So an 0W 30 oil will remain very fluid at very low temperature while maintaining it's viscosity at operating temperature. It will have a very high viscosity index and will use very high quality base oil, along with viscosity index improvers (see links above), in order to achieve this.

It lubricates the same way as any other oil, buy providing a hydrodynamic wedge of oil that lifts and separates the moving parts in an engine, much in the same way a moving boat raises up on the water. Anti-wear additives in the oil provide self sacrificing layer of protection as the parts begin moving until the wedge of oil develops (boundary lubrication conditions) and lubricity additives provide additional friction reduction. It maintains pressure as the supply of oil from the pump exceeds the required volume of oil in the engine (remember, pressure is resistance to flow; pumps supply flow). It's all pretty basic stuff. There is a whole field of study for this, it's called Tribology.

 

Steve, Steve, Steve, I think you just want to argue. You think you're arguing with me, you're in fact arguing with an entire industry who's job is the study and development of lubricants and wear reduction. Your arguments are analogous to somebody who's entire knowledge of electricity is that they sometimes change a light bulb arguing with you about the nature of alternating current.

Here, educate yourself.

http://web2.mendelu.cz/af_291_projekty/files/11/11-jmd36.pdf

http://www.viscopedia.com/viscosity-tables/substances/sae-viscosity-grades/

Well, all those oil analysis labs all across the country should just get rid of their viscometers and measure the viscosity like this!!

Dude, you are dreaming. If we took 2 oil pans, filled one with SAE 40 straight grade oil and one with 15W40 and heated each one up to 100C and pulled the plug, side by side, if you didn't know which was which you couldn't identify them. Period. Disagree? Prove it. Let's set up a blind test.

You remind me of the high end audio guys that swear they can hear the difference in speaker wires, yet when confronted with a blind test they couldn't identify between their beloved high end wires and coat hangers.

 

This is correct, there have been multiple changes over the years, but the performance level has continued to go up with those changes. CJ-4 engine oils have been around for 10 years, there has been no problem with increased wear with those oils, in fact the opposite is true. Modern diesel engines are now lasting >twice as long as previously expected life span. I have a customer, a large mining operation in multiple states, that currently tears their Cat engines down at 24,000 hours for their "first life" overhaul. What they find are engines that look immaculate inside, with very little wear at all. The problems they typically see at that point are with sealing surfaces, and they are now going back to Cat and other engine mfgr's and telling them it's time to upgrade their sealing materials and clamping forces on head bolts, etc. If they can keep the engines tight and leak free they believe they can get to 30,000 hours before the first overhaul. Wear of lubricated parts is not a problem. Now, they aren't using Rotella, but they are using a CJ-4 engine oil.

Note, CK-4 engine oils roll out to the market the beginning of December, this year.