Oil viscosity - why the 20W-50 BS?

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airwoofer

airwoofer

Drivetrain limit explorer
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The car I bought from a friend's widow just had a purple 508 cam installed. The guy never heard it run before he died but he did leave a note saying to use Valvoline 20-50 ZR-1 with zinc. The local speed shop is a Mopar house and they carry and recommend Brad Penn 20-50 green oil which I ran in the stroker a while. I was noticing that the oil pressure is getting slow to rise and the engine is very cold blooded on first start after sitting for a week or so. I put in 10W-30 Brad Penn this oil change and the cold blooded nature went away mostly and I still have 60-70 pounds at high idle after the cold start.

Why the heck are people telling us to run that thick oil? I believe it is hurting the engine especially when cold. In fact I have started the practice of turning the engine over without spark until the oil pressure comes up. I use a drain back blocking valve Purolater oil filter.
 
Why the heck are people telling us to run that thick oil?
Click to expand...


because the oldheads still believe that stuff and have brainwashed many younger people..


its the same bullshit as:

have to change the oil every 3000 miles
a 904 won't hold any power and you have to run a 727
you can't go more then a 3000 stall converter for the street

etc..etc...etc...
 
This may be a flukebut I ran castrol 20/50 in my 1991 Chevy pick up for 14 years and 256,000 miles. The break in oil was the only 10/30 wt I used.
Moe
 
Good diesel oils are a decent compromise. Not too thick, good zinc levels (at least they used to be, I've heard some of them changed?)

The most common Diesel Oil is 15w40
 
What Joe said, for the most part.

There are instances where special oils are needed. But for the vast majority, nothing fancy is fine.

My 97 Neon had it's oil and filter changed in November of 2010. It's got about 200K on it, I bought it at 67K in '02. It's had about 7 oil changes in that time and gets 30+mpg. My truck, last dropped in October of 2010. My '65, I've owned since '09 and still has the oil and filter it came to me with in it. I hate changing oil.
 
i run 15-40 delvac in my truck and race car,being a truck mechanic,my dodge truck has 250.000 on it,never leaks,never uses oill between changes,doesnt smoke,my 5.9 never has been apart
 
I'm using 15w-40 conventional diesel oil with Comp Cams break in lube to break-in the engine, then racing with 5w-20 Amsoil Dominator synthetic.

All the new vehicles recommend thinner oils not only for mileage and quicker circulation, but OEM tolerences and ring seals are better these days, so thicker oils are not needed.
 
abodyjoe said:
because the oldheads still believe that stuff and have brainwashed many younger people..


its the same bullshit as:

have to change the oil every 3000 miles
a 904 won't hold any power and you have to run a 727
you can't go more then a 3000 stall converter for the street

etc..etc...etc...
Click to expand...

When you have a dozen cars with at least 250,000 miles, I'm not willing to try the latest wizbang idea. I'll keep running 20-50, even in my ACR Neon with 250,000 miles. It still runs like new. If you feel lucky, give something else a try.
 
airwoofer said:
The car I bought from a friend's widow just had a purple 508 cam installed. The guy never heard it run before he died but he did leave a note saying to use Valvoline 20-50 ZR-1 with zinc. The local speed shop is a Mopar house and they carry and recommend Brad Pitt 20-50 green oil which I ran in the stroker a while. I was noticing that the oil pressure is getting slow to rise and the engine is very cold blooded on first start after sitting for a week or so. I put in 10W-30 brad Pitt this oil change and the cold blooded nature went away mostly and I still have 60-70 pounds at high idle after the cold start.

Why the heck are people telling us to run that thick oil? I believe it is hurting the engine especially when cold. In fact I have started the practice of turning the engine over without spark until the oil pressure comes up. I use a drain back blocking valve Purolater oil filter.
Click to expand...

the 20-50 is for summer and the 10-30 is for winter

i dont think you should run 20-50 year round unless you are in a very hot climate

however when it's 100 degrees out you should be runnin 20/50
 
These old engines don't know what the hell weight the oil is. As long as the dipstick is full.
 
I run 10-30 year round in the Demon and grocery getter, works just fine. No need for the thick stuff unless you're racing or got a crap load of horespower, 700 plus. Diesels are a whole different kettle of fish with their very high compression/combustion hence very high rod and crank bearing loads hence 15W-40.
 
Here is my 2 cents for what it is worth. Multigrade oils are oils that have viscosity modifiers in them. When oils are graded they must pass a flow test. The graded is determined by that test. A 20W-50 oil flows the same as viscosity grade 20 oil when cold. As the temperature of the oil increases the oil flows like grade 50 oil. Multi viscosity oils were developed to compensate for the extreme difference in oil flow rates from cold starts to normal operating temp. The issue arises in the fact the the viscosity modifiers do not last as long as the oil. This results in that 20W-50 oil flowing like a standard 50 weight at cold temperatures.
Another issue is that it takes energy to move the oil through the system. This is why you want to select an engine oil that falls within the normal temperature extremes of the environment you are driving in. If the weather is continually below zero you need a thinner oil. If you live in an area where the temperature never drops below 60 you do not need a 20W oil. That is why there are suggested temperature ranges for oil use. You want to use an oil that is thick enough to force the moving metal parts away from each other but not so thick that your engine has to work to move it through the system.
~Michael
 
I did not know that Brad Pitt was making oil.......... I have heard of Brad Penn green oil. LOL I am like other I have ran both 10W30 and 20W50 in different applications, but I do think running a good oil with a high level of zinc is a very smart thing to do on theses older flat tappet cammed engines.
Matt
 
66fs said:
When you have a dozen cars with at least 250,000 miles, I'm not willing to try the latest wizbang idea. I'll keep running 20-50, even in my ACR Neon with 250,000 miles. It still runs like new. If you feel lucky, give something else a try.
Click to expand...

and i have cars go well over 100k running 5-30. oil has come a long way. want to stay in 1950 then so be it.


like i said earlier..


its the same bullshit as:

have to change the oil every 3000 miles
a 904 won't hold any power and you have to run a 727
you can't go more then a 3000 stall converter for the street

etc..etc...etc...
 
I had always been told that the only reason to run heavier weight oil is to permit you to open up the clearances in the motor. A couple of machinists I've talked to concur, that if you take an extra tenth when you turn a crank, you reduce friction in the motor by better floating the crank and rods in oil. The upside, better rpm capability, less friction, and less wear under heavy duty use. The downside, you have to run heavier oil to keep the pressure up.

It's the same reason some drag racers around here pull worn out junkyard short blocks, 50 weight oil H/C/I and a 200 shot, and run 'em 'till they blow.
 
I put together my 360 with bearing clearances on the loose side and a standard-volume oil pump so I'm planning on breaking it in with Shell Rotella 15W-40 then switching to a synthetic 10W-30 or -40. If your engine has good oil pressure at idle when hot (i.e. just getting off the freeway and idling at a stoplight) with 10W-30 or similar oil there's no point in using thicker stuff; all it will do is rob power and gas mileage and make your engine more susceptible to wear during cold start-ups because it takes longer for the oil to circulate.

You should run the lightest-weight oil you can that still gives good oil pressure at hot idle; that gives you the most efficiency.
 
I too was raised up on the thinking that the thicker the oil the better it was. After seeing reports on how fast 40 weight oil flows at 20 degrees vs. 20 weight I saw things in a different light. It's entirely possible that an engine may need 20w50 oil if the clearances are loose but running thicker oil than you need is wasting energy and since it's cold flow rate is much slower it wears the engine faster. It all depends on the engine build.
 
Whatever works. I was told not to run "car" oil in my one sport bike as it needed "special sheer additives" because the oil also circulated thru the clutch & trans. 100k miles later, all with Mobil One the bike still had the original clutch and never had any metal on the magnetic drain plug.
 
airwoofer said:
The car I bought from a friend's widow just had a purple 508 cam installed. The guy never heard it run before he died but he did leave a note saying to use Valvoline 20-50 ZR-1 with zinc. The local speed shop is a Mopar house and they carry and recommend Brad Penn 20-50 green oil which I ran in the stroker a while. I was noticing that the oil pressure is getting slow to rise and the engine is very cold blooded on first start after sitting for a week or so. I put in 10W-30 Brad Penn this oil change and the cold blooded nature went away mostly and I still have 60-70 pounds at high idle after the cold start.

Why the heck are people telling us to run that thick oil? I believe it is hurting the engine especially when cold. In fact I have started the practice of turning the engine over without spark until the oil pressure comes up. I use a drain back blocking valve Purolater oil filter.
Click to expand...

What's the big deal? He was probably just trying to give you the benefit of his experience. It's your car now, do what you want. I lived 5 years in South Dakota and maybe ran as low as 10W30. Never hurt any motor. Use a good grade and you should be fine.
 
abodyjoe said:
and i have cars go well over 100k running 5-30. oil has come a long way. want to stay in 1950 then so be it.


like i said earlier..


its the same bullshit as:

have to change the oil every 3000 miles
a 904 won't hold any power and you have to run a 727
you can't go more then a 3000 stall converter for the street

etc..etc...etc...
Click to expand...

The only BS I can see is "if I want to stay in the 50's". What I do, has proven that it works. Why would I chance going to yours??? Better gas milage? .001 of a second faster in the quarter mile? Not going to happen. I even run straight 30W in the summer. What you do with your money or car is your business. I don't care.
 
66fs said:
What's the big deal? He was probably just trying to give you the benefit of his experience. It's your car now, do what you want. I lived 5 years in South Dakota and maybe ran as low as 10W30. Never hurt any motor. Use a good grade and you should be fine.
Click to expand...

The engine was a lot less cold blooded with the 10W-30 and idle oil pressure was just as high. Like I said, I think the thick oil was hurting the engine and robbong power just to pump it through the passages. I will stay with the thin stuff.
 
I been running 20w--50 not street legal oil in my 340 since day one, works just fine and its been driven hard at some points--wide open blasts in top gear in mid 90 degree temps//those young punks and their hot japan motorcycles, lol

Thicker oil also clings better--great if you don't drive the car everyday
 
dodge freak said:
I been running 20w--50 not street legal oil in my 340 since day one, works just fine and its been driven hard at some points--wide open blasts in top gear in mid 90 degree temps//those young punks and their hot japan motorcycles, lol

Thicker oil also clings better--great if you don't drive the car everyday
Click to expand...

Not street legal oil? what the hell do they do? pull your dipstick and put the oil on litmus paper? I've never heard of a kind of motor oil you weren't allowed to run on the street. what's it got in it? Phosgene?
 
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