Oil viscosity - why the 20W-50 BS?

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derrangedgadgeteer said:
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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He probably means it doesn't conform to industry specs for on-road/highway vehicles, it probably has the extra zinc and other stuff that puts out a bit more pollution and is only legal for use in 'off-road' vehicles. But with a classic 340 I'm sure it doesn't make much of a difference lol...
 
my friend has a Hemi Dart and runs the heavier oil to keep the engine cooler, well mostly the bearings due to large clearances, using light oils on cars with large bearing clearances tends to "blue" the main bearings, aka f***ing them up...

I guess it's logical but we run 10-30 in everything we own and haven't had problems yet
 
I ran my first 340 with 20/50 because i had too! hot idle oil pressure was low.
My 2nt 340 i built better, oil pressure would peg my 80 psi gauge when cold and idle hot at 30 psi. Ran it that way for 15 years, no problems.

The last 3 year it's been running on syn 5w30.........idles better drives better, and picked up several ten's in the 1/4 mile......
Motor is tired now and will be retired this year for a stroker.

NO the light oil didn't ware my motor out......it's just 17 year old and i don't want to throw a rod thru a .020" over 340! LOL

If i live in a 100+ degree climate, i would still us a 20w50......If not, us as thin of oil as your oil pressure (aka You) is comfy with.:director::D
 
My '72 Coronet is a hair away from 200,000 on its original , untouched 318 ; 70,000 of those miles are from my use .

I've been running Valvoline 4-Stroke 10w-40 (e.g. , wet-clutch motor cycle oil with ZDDP) and Lucas Oil Stabiliser in the colder months (usually Oct.-Apr. here) and 15w-40 / Lucas in the warmer months.

20w-50 is not recommended in 273's & 318's (more-so 318's) in factory-stock configuration , as the distributor shaft and oil pump drive are prone to snapping due to being strained by thick oils . This was especially a problem in the 1970-1972 engines due to some casting flaw (or so I've heard for the last 20+ years ... ).

So long as you're using a ZDDP-rich oil on flat-tappet cam engines , use whatever weight you desire ...

... just play keep-away from Pennzoil and Quaker State unless you want waxed-up rockers and a plugged oil pickup :D
 
66fs said:
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.
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lol.. i'm sure a lot of people said they liked their horse and carriage too. hell it worked well why change to a car.. :)
 
derrangedgadgeteer said:
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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Not For Street Use means it has enough "stuff" in it that it cannot pass the EPA testing or carry the "starburst" medallion. Think of it like race fuel with lead vs pump high test. I use Not For Street Use VR-1 in applications where the spring pressures and cam lobes need the extra protection. It's like the Gibbs and Brad Penn oil. I dont believe any of those carry the sunburst SAE medallion.
 
Well I had a little window of no rain and dry roads so out came the fish yesterday with the 10W-30 Brad Penn oil. Starts better, cold start "idle" better behaved, cold "idle" pressure (1300-1500) around 70 PSI. When the engine got hot @200* the 650 RPM idle pressure was 20 and 1500 is 40 with pressure rapidly going up to 60+ with RPM. I do think the water is running a tad higher with the thinner oil and not sure why that would be the case...unless one thickness has more synthetic. I believe that syn oil does not transfer heat as well (why it can be used at higher temps) and that may be why. Also coulda been the water level in the rad as it was a tad low - putting in more dropped it by about 20*.

These cars are so fun on the back country roads! Need to quiet mine down a little so it isn't cop bait.
 
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


Humm the older guy that built my engine proved alot of these " new Guys" wrong. Told me I couldn't run this or needed that" I'm glad I didn't listen to them, new guy" Oh you can't run a 1 7/8 header on a 408. Bullshit I am and it's great. Oh that 670 carb is amll bullshit. I'll listen to the guys that built engines in 50's and 60''s anyday!!!!
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20-50w ...20w when cold and up to 50w when hot 'oil viscocity lowers with heat'

It's about film strength people, the bearing and the rest have an oil film on them from the previous run in ...so how fast the oil flows at start up is not a worry, maybe it was in the 50's though.. ;)

Op, u going on about how you still have over 70psi at a cold start with 10-30 w is laughable, u could run 5w and have that much, its after you run it, run it hard, and for a long time. Try actually driving the car 5 hrs down the freeway and then exit and come to a stop...then peek at the gauge and see how lil oil psi u have compared to 20-50w. See I don't know about the rest of you...but I turn 3-4k rpms going down the freeway with my 340...while it runs cool and has a deep pan the hangs in the breeze...the oil is getting hot.Try drag racing all day, how about road race? If you simply putt around town and hand your own *** over to brand x for fear of speed or breaking something, then I'm sure 10w will suffice for you. The other main thing is bearing clearance, how much clearance do newer 4 bangers have compared to the .0025 or so we have in our v8's?
How about the quality of oil u run in the first place? I don't run over the counter swill, though today's swill I'm sure is fine with exception of zinc content....try a better oil, try to understand the meaning of multi viscosity
 
67mopr said:
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


Humm the older guy that built my engine proved alot of these " new Guys" wrong. Told me I couldn't run this or needed that" I'm glad I didn't listen to them, new guy" Oh you can't run a 1 7/8 header on a 408. Bullshit I am and it's great. Oh that 670 carb is amll bullshit. I'll listen to the guys that built engines in 50's and 60''s anyday!!!!
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Oh yea? What did he prove wrong? And glad ya didn't listen to who about what?
 
Cudafever said:
I ran my first 340 with 20/50 because i had too! hot idle oil pressure was low.
My 2nt 340 i built better, oil pressure would peg my 80 psi gauge when cold and idle hot at 30 psi. Ran it that way for 15 years, no problems.

The last 3 year it's been running on syn 5w30.........idles better drives better, and picked up several ten's in the 1/4 mile......
Motor is tired now and will be retired this year for a stroker.

NO the light oil didn't ware my motor out......it's just 17 year old and i don't want to throw a rod thru a .020" over 340! LOL

If i live in a 100+ degree climate, i would still us a 20w50......If not, us as thin of oil as your oil pressure (aka You) is comfy with.:director::D
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Bingo.lol
If 10w suits you, then go for it.
 
Dartman1969 said:
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
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I always changed my oil when it looked like it was getting dirty. Never considered the breakdown of the viscosity modifiers. Guess it's time to change.
 
Everyone has an opinion. Me, I run Rotella T6 5w-40 and here's a few reasons why.

- I need to run at least a 40w oil to keep hot idle pressure up. A good 10w-30 was only good for ~10 psi hot oil pressure in my engine, and while still ok (1 psi per 1k rpm rule), wasn't high enough to make me comfortable. My engine bay gets HOT.

- I like the lighter viscosity for cold weather start-up. I don't know about you guys, but when my engine starts it shows no oil pressure for a second or so. Running the 5w oil give me a little peace of mind knowing it will get to vital parts a little faster, even if only by fractions of a second.

- Now this isn't necessarily the most important thing, but at $21.36/gal (Walmart), it's a good value for a name brand full synthetic.
 
Someone said it in one of the posts - it all depends on the motor and build of the motor. Older motors are not made the the tolerances of today's engines so you can't compare the two. A stock or close to stock build of an older engine probably does not need a heavy weight oil and does not benefit from it. The caviots to this center around temperatures and use. If you drive around in MN in 30 below zero weather, you definitely don't want to push 50W through the engine. If you drive around in Houston in 100 degree weather 50W may be best. If you run the engine hard in hot weather heavy is better. Then you get into high performance engines, loose tolerances, high compression, high rpm use - heavier weights are better.
One other thought - if you run a motor that does not have catalytic converters behind it - run a high zinc oil. I don't care if it's a mild build, hi perf, roller or hydraulic, use the zinc. If can't hurt and can only help... My $0.02!!
 
I run 20w50 VR-1 Val in the Dart. I ran Mobile 1 once in it and the lifters started leaking down. I changed the oil back and haven't had the problem. I run and like it.
 
moparlover said:
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
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Bingo. I,m not running my rb stroker in Texas heat in traffic with watery oil. Aint gonna do it.Sure 5-20 is great at the track or in a mild street motor but not for hot blooded big inch beasts.
 
alot of stuff from venders, mechanics that didn't know their *** from a hole in the ground.. of all ages mind you. I know some of the younger ones that are damn good... as far as about what, see my post.
 
I run Pennszoil 10/40 in my vehicles and 30w in everything else.
I also let them warm up for 1 minute before I move anything.
I do this to everything with a motor at cold start up.
I then take it easy till operating temp is achieved, after
that I feel safe to work it.
I add zinc to the oils on older motors and lead substitue
to the fuel.
I add Stabil to all fuels starting in October.
I also treat with Slick 50 or the generic it all my aircolded engines
a couple times during there lifetime.

What ever you use, change it on a schedule, filters included.
There isn't anything you can fix in a motor or machine that is cheaper
than clean oil and a squirt of grease.
 
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