Engine oil

Looking on the internet for information about 15W40 oil. I never understood until now how the multiviscosity oils work. Always thought when an oil got hotter it got thinner. Read that with multiviscosity this is not true. When starting with cold engine the oil is 15 weight and once engine gets to operating temperature the "thickening inducer" has changed the oil to 40 weight. Sounds outstanding to me.

Perhaps there's more to this than what I've just mentioned.

Don

***Always thought when an oil got hotter it got thinner**
Don, it still does, It just does not get as thin as the old oils did. It does get thicker when cold, just not as much as the old oil.
When cold it is as thin as the old 15W, when hot it is as thick as the old 40W.
Hope that helps.

The great milage/hrs people and truckers are now experiencing before major overhaul can be attributed to:

More accurate machining of engine parts?
Better engine oils?
Better metals?

I assume all of the above but guessing better oil is the main reason for present day engine durability.

Anyone?

Too. Are farmers now getting a lot more hours out of their tractor engines than they used to? How is farm tractor engine life different now than say 30 years ago? 1980 a farmer could expect 5000 hours before major engine problems while now 8000 hours is more common? Just guessing here.

Don

THANKS ... I too .. never figure that out ...
Now you explain it so I can understand it ...

Mark

Years ago in aircraft school they explained oil weights,if I remember correctly the oil ratings are by the viscosity of the oil or resistance to flow,a multi weight oil has the propertys of a 15 weight oil at cold temps. but the lubrication and viscosity of a 40 weight oil at operating temp,but that's been over 40 years ago and I can barely remember what happened last week! Hope this helps.

The descriptions on the oil is correct. 15 weight when below a certain temp and acts as a 40 weight above a certain temp(can't remember the temps off hand). The impurities in conventional oils are one of the main things that cause them to thicken in the cold. Synthetics (quality synthetics anyway) do not have these impurities and flow much better when cold. My car cranks just about like it does in the summer with synthetics.

In regard to your engine question, lasting longer probably yes to all your thoughts. Better oils, better machining, better materials, better quality control ect ect. Also, I think people tend to change oil more often then used to. As a kid we changed the cars at about 7000 miles now alot change a 3000 miles and alot of folks are getting 200000 miles out of cars when they would be shot in the 50's, 60's - 70's before 100000 miles.

Don, I think the higher mileage/life of the gasoline auto engines can be attributed more to fuel injection than anything. The carb engines were more prone to flooding. The excess fuel washes the oil from the cylinder walls. I've gotten 200,000 miles from a FI Buick engine, and it didn't use a quart of oil between changes. Never had a carb engine do even half those miles without burning an occasional quart.

A personal opinion from a casual observer.

Paul

I think all of the above.
I think that is you used 1940 oil in a modern engine, it would quit on you shortly.
The one I have a hard time adjusting to, but have accepted it, is the use of the thinner oil in my newer engines. Must be very close, precision fitting. 10 Weight only in my ranger. I use ford 10 weight sythenthic (sp?) and it sure starts easy on cold mornings.
FWIW: I loved (when I farmed) 15W40 diesel oil in my older tractors and pickups. Ran it in every thing. Did not like 10W30 at all on hot days in a working tractor. .

all right then am I "OK" to put 15 40 in my tractor (1973 diesel modle) for year round use?

For tractor diesels going back to the 60s, 10,000 hours was usually expected for a properly maintained farm tractor diesel. Not 5000 hours, but I was a Deere mechanic. Are you saying other brands had lower life projections?

I don't know about other parts of the country, but in this area the only oil anyone uses in gas or diesel tractors is Shell Rotella 15w40. I also use it in my 68 and 95 Ford pickups. I use mobil 1 in my Subaru car and Motorcraft 10w30 in my Lincoln

The way to find out is to get a data sheet from the oil manf.

The viscosity is measured in SSU. That stands for Saybolt universal seconds. It has been 20 years since I had hydraulic school. But if I remember SSUs is how long it takes for oil to flow through an orfice at a certain temp.
I think that all oil gets thinner as the oil is heated.

Lots of people run 15-40 year round. I agree that most well maintained diesels should get 10,000 hours or more before rebuilding. Of course it depends on the engine and the application. I know a guy that dug pipelines with a Detroit 6-53 in an excavator. Those engines ran about 2650 rpms and required a major overhaul after 3000 hours. Newer excavators will easily go 10,000 hours but a lot of them are only running around 1650 rpms. Lots of tractors from the 60's could go 10,000 or more hours. Dave

The viscosity standards for oils are set and oils must meet those standards. But I contend that certain oils have either more impurities in them (penzoil) or actually break down at performance peaks (valvoline in racecar)

Also noted is that I don't agree with the mention of better metals above. I agree with better machining and that oils are improving but many different metals today have way more imperfections than years ago. They are just cast or machined in a more efficient engineered manner.

Any good welder or torch user will tell you that imperfections are way more common due to recycled materials being used. My welding supplier gets me different rods when repairing old tractor cast iron vs. newer tractors.

Just my thoughts on oils vs metals. Sorry about rambling on

When I started working as a Diesel mechanic in 1980 there was still a lot of people using series 3 or straight 30 weight,heavy duty Diesel oil.And there are engines that may even like that oil better still because it might stay in an old engine with old seals a little better.But thats about the only reason.The bearings surely will have a shorter life using straight 30 weight.
If a trucker had a 318 Detroit 2 stroke engine in his rig in 1980 he might get 150,000 miles before an overhaul.
I also have seen the difference in power of the 2 stroke engines and the 4 stroke Cummins and Cat engines.There really is not any comparison in the hills.Cat or Cummins will tear them up because they have way more torque.
If he had a Cummins diesel engine he could maybe get 300,000 miles before an overhaul.Sure some people could do better in both cases,but for trucks with drivers on them running hard that was about all they could count on getting out of a over the road truck.Macks were better if taken care of.
They switched to 15-40 oil and got rid of the trucks with 2 stroke Detroit engines.We started replacing bearings in Cummins motors at 300,000 miles and sometimes they didnt even need it.Overhaul around 500,000 miles.Then Big Cam 2,3 and 4 Cummins engines all improved the life of the engines to where by Big Cam 3 Cummins in maybe 1986 some engines were getting a million miles before over haul.Now of course some people could get better some worse but it was starting to get to where lots of engines got at least 750,000 miles by 1989 with maybe a bearing change at 400,000 miles.They way,way improved the efficiency of oil coolers on the Big Cam 4 Cummins and they improved the water system.They also put restricters in the water system and a new type of radiator that had 2 sections built in it to cool more efficiently,and then they started getting a Million miles a lot more.Cummins always had problems with liner erosion because they flowed so much in their cooling system.Old engines like that need a water filter on them and need the water tested regularly to get the most miles.Slowing the water flow down also made the engines live longer because it helped the liners last longer on the older engines.So by improving the aftercooler to air to air and lowering oil pressure so the oil quit foaming and lowering the flow of cooling,raising the turbo boost rate with more fins on the blower side,better rings,better pistons,better gaskets,better training of mechanics and a little better tolerances on their products they went from 300,000 to a million miles before over haul.The part the oil played is 15-40 is a better fit from cold to hot than straight 30 weight.Its better when its cold because its thinner and it protects better when its hot because its thicker.Bearings taken out of a 300,000 mile Big Cam 1 Cummins even with 15-40 oil are wore out showing copper and about ready to spin sometimes,after 500,000 miles in a Big Cam 4 with 15-40 they look good,no copper usually unless its been hot or had a defective oil cooler or something.
Cat is similar to Cummins but also the first engines to make it to a million miles because the parts inside the Cat engine were better harder metal than what was in a Cummins.Now Cummins has hard metal liners too.Both Cat and Cummins were way ahead of Detroit 2 strokes.Those engines had been around since the 1930s and didnt have a whole lot of improvements.At the last they had better rings to where you could get 300,000 or more miles out of them.
Newer Cummins and Cat and DDEC inline 4 stroke Detroits kind of designed by John Deere maybe now regularly go a million miles without much trouble.Its better management of air and fuel and oil that sticks to surfaces better,better cooling and better metals.Air to air helps too.All of this together with sleeker bodies and overdrive ratio transmisions and higher geared axles all work together to make this possible.Also reducing the maximum Rpm from 2400 down to 1950 on Cummins engines and gearing the truck to work at those Rpms.
Some people can tear up an anvil in a sand box.I have seen trucks that didnt have 400,000 miles on them missing and smoking oil leaking everywhere and even a few with a blown engine.You have to check the oil every day,you have to change it regularly,and you have to fix whats wrong with it like water leaks and oil leaks so it can run instead of blow up.Then once in a while a bad one gets through and is nothing but trouble.For the most part its possible to go past a million miles now without major problems as long as good maintenance is done.
I dont know anything about the very new engines except they probably wont go as far,are choked back because of emissions crap and the newest ones will be worse.Things are going backwards it seems like now.
So along with lots of other things,15-40 at least tripled and potentially way more raised the performance of crank bearings.Also noticed that engines using 15-40 Shell were a lot cleaner inside than ones using series 3.The 15-40 oil was a big improvement in every way over straight weight oil from what I saw.

I think you're mistaken.

Ford is telling people to 5W20 in their new cars now. My Freestyle gets 5 quarts of Motorcraft 5W20 synthetic blend and one quart of 5W20 Mobile 1 every oil change.

Tolerances are a lot tighter and oils are a lot better now, but I still change mine every 3000 miles because I don't think that light of oil will hold up well to thermal breakdown.

The other reason Ford (and a few others) switched to 5W20 was fuel mileage. Even though that light of oil will only have a minor differance in overal fuel economy you multiply it by the million plus cars Ford sells every year and it helps them meet mileage requirements as specified by the government.

Ford posted results of a study recently, stating that auto engines could last two times longer if higher viscosity oil was used. But, since they already greatly outlast warranty periods, the low viscosity is used to help meet EPA fuel mileage requirements.

Thanks to all of you for your great responses to my "engine oil" post.

Oil, as you all know, is at the heart of engine longevity--along with other things. Makes it a pretty important subject and important to know the truth about it.

Appears if we had a vote in this group as to the best engine oil to put in your tractor (both diesel and gas?) Shell Rotella 15W40 would be the winner.

Still I've been real curious for quite awhile about the synthetic oils some of you mention. Are they truly superior to all other oils? I know many people use them but the majority don't.

If these synthetic oils are as superior as some people think maybe most of us have been making a big mistake by not using them.

Don

Ford also expected 10K hours on their engines for everything after 1965 at least...
There were lots of them that produced the results too.
I could never figure out where this 5K figure comes from?

Rod

Depending on the application, Detroit 2 cycles can last a very long time. There used to be Shell Rotella S for the Detroits. The S stands for single grade oil. Detroit 2 strokes call for single weight oil. I've heard of lots of problems with the 92 series Detroits because they basically put more HP into a 71 series design but didn't beef up the bottom end enough to handle the extra power. Cummins 444 are supposedly another problematic engine. Dave

Nedd,

Do you have any evidence that Pennzoil has "more impurities" or that Valvoline "breaks down"? You would need a fairly sophisticated lab to prove these statements. By the way, another word for "impurities" is "additives".

Whether or not recycled metal is used in a product doesn't have a lot to do with the level of impurities in it. Remember, "virgin" steel was once iron ore.

I tried 15W-40 Rotella in my Ford gasser, and I found it's just a bit too thick for easy starting in subzero weather. I subsequently switched to 10W-30 and it starts fine down to at least -10 degrees F.

When I mentioned materials below I was referring to the improvements in alloys and methods of producing iron and steel. They are better than they used to be. and I think this is true for most domestic automotive (& trucks and tractors) applications. We used very good alloys in brake rotors/drums at Bosch. Aftermarket parts... who knows... they probably mix in some dirt and rice as filler. since so much steel and cast iron aren't made here you will probably see some poor steel and iron in non engine/trans components.

I've rebuilt 4 different engines that used penzoil exclusively and three had plugged up lifter valleys (4.3 and 2-350 chevys) other one was a 2.4 with crud on the rocker arms.

Now granted the last one was in 1998 and since then I refuse to buy anything that has penzoil used. Maybe things have improved or they use better detergents. You're right that maybe I overstepped in mentioning the impurities but that has been my personal experience and has been confirmed by many mechanics that I have dealt with.

And as far as metals go. I believe there is no good way to displace all the carbon atoms from grade 8 steel melted in with iron or steel that contains less than 1 percent carbon atoms.

I don't work at the foundary but I bet there is not a person sifting through and getting rid of the grade 8 bolts and nuts before the old steel is melted down.

Same theory applies to all liquids. There are parts of the ocean that are saltier than others and there is more sugar at the bottom of your glass of kool-aid.

You just can't evenly displace carbon atoms in steel that has been recycled. But there is a tolerance level that does get met by the steel industry.

Just my 2 cents.

Actually it is not very difficult to remove carbon from steel. Cast iron runs about four percent carbon so if there is too much cast in a heat you will have a lot of carbon that needs to be removed.

I worked in a steel melt shop for a while as an assistant on the electric furnace. After all the metal charge in the furnace was melted we had to take samples to the lab and they would send the results back so we knew how much of each element had to be added to get the right mixture. If the carbon level was too low we would dip the three carbon electrodes in the molten pool and carbon would be added. To remove carbon you simply pumped oxygen into the molten pool using a length of black steel pipe. The electrical arcing would mix the steel so that it would be uniform in texture. It would take about a half hour to raise the temperature from about 2500 degrees where it was all melted to 2875 which was the temperature that the furnace was tapped. We melted 80,000 lbs of recycled steel in each pour.