slant 6 oil weight

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I'm a little late to this thread. This is my opinion, and others have theirs.
1) Never use a straight grade oil (ie 30 or 40 ),or a non detergent oil, in any auto engine made in the last 60 years.
2)I run "house" brand 10-30 in all my cars, including my race cars. My truck is a 4 cyl, tows my race car, and has 394,*** miles on it with all original engine parts, except for timing chain. I have not had a oil related engine failure in 40 years.
3) I feel syn oils are better then "dyno" oils, but not enough better to justify the cost. Current "dyno" oils are excellent. There are exceptions to using Syn oils, I have one customer that really "beats" on his engine. Heavy loads, highspeed interstate, in drastic temp changes. Him, I recommend syn oil.
 
I have not run 100% synthetic in my old cars yet. I currently use Rotella but I get zinc additive from the Summit store when I'm there and use about a half bottle per oil change. I don't have any cars with radical cams or high spring pressures so I'm not too concerned. However, I do know guys that have wiped their cams and they are typically more stressed engines than my junk.

My "modern iron" is a different matter. (if you call my 03 Neon every day driver modern that is) I switched to Mobil 1 about 15 years ago in all my new stuff. In the last 6-7 years though I've been buying the Walmart brand 100% synthetic. My son is a gear head too and he heard that supposedly the Walmart syn is made by Mobil. I don't know for sure. My reasons for running syn is that last month we had several mornings where the temp was below zero at start-up and I just want the oil moving quickly at those temps. Car sits outside while 3 60's cars are in the garage. Something like 90% of engine wear occurs in the first minute or so. I use 5W-30 in Winter and 10W-30 in summer. Also, I extended the change interval to 8000 miles and need to add a half quart at about 4000. As I get older, I like not having to crawl under the car as often. The engine internals seem to be cleaner when I take my junk apart. Neon has 208,00 miles on it in a bad climate and the cylinder compression is within 3 psi on all 4 holes so I ain't switching. I also use genuine Ohio-sourced air in my tires. Man that stuff really fills them up good.

Once the 225 is together, I'll probably use dino oil for 500 miles or so and then I think I'll try the Walmart syn. WTH, it may even be worth 1 HP and I need all I can get. I still have my suspicions syn leaks more than dino but the 225 will have all new gaskets and I'm hoping it will stay where it belongs. It does help keep the underside rust free though.
Just my 2 cents.
 
roccodart440 said:
Run the weight that produces the oil pressure you need. I run 0w-40 Mobil One. I only run Mobil 1. I only run full synthetic in all my engines.

In regards to Zinc. Don't pretend to be a chemist. Buy an oil that has the proper lubrication for your engine.
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He's talking about a /6 not a Hi-po engine. /6 Calls for SAE oil only !!
 
roccodart440 said:
I never said he needed lightweight oil.
I never said he needed synthetic oil.


I said to use the weight oil that provides the pressure he needs.
I said that I use synthetic in everything I own and that Mobil 1 is my choice.
I said do not play chemist. Buy an oil with the proper lubricating properties.


:violent2:
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Control oil pressure by the weight of oil ? WTF are you talking about, if you have to run 50W to get 5 lbs of oil pressure... Dude I don't believe people here are that stupid. You work for CNN. LMAO
 
I'm using Lucas Hot Rod and Classic 10w40 in my slant. That or Valvoline VR1 10-30
 
Thumpr said:
Control oil pressure by the weight of oil ? WTF are you talking about, if you have to run 50W to get 5 lbs of oil pressure... Dude I don't believe people here are that stupid. You work for CNN. LMAO
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Who said I was recommending running thicker oil?

In fact, I was thinking some people run thicker oil than the engine needs and I have personally seen that result in oil pressures that are too high.
 
Thumpr said:
Control oil pressure by the weight of oil ? WTF are you talking about, if you have to run 50W to get 5 lbs of oil pressure... Dude I don't believe people here are that stupid. You work for CNN. LMAO
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Yes, lots of folks "adjust" oil pressure by changing viscosity because not everybody has the time/means/desire to rebuild an otherwise OK running hobby car, if it ain't burnin' a qt. every 500 mi. and leavin' a haze why? In a perfect world You wouldn't, but it ain't a perfect world for most, so increasing viscosity to bump the frictional factor/volume demand is acceptable to most.
And regardless of CNN's MO or agendas, not every employee of CNN shares those, let's leave that crap out yet another "What oil do I use?" thread.
 
I'm not sure why a 5 year old thread got resurrected as the OP's question was already well answered. I'm also not sure what Thumpr meant by "SAE oil" - presumably a Passenger Car Motor Oil (API S-category, like SN) rather than a Heavy Duty Engine Oil (API C-category, like CK-4). OEM slant six valve trains probably don't require the added ZDDP of a HDEO but the added protection for the tappets certainly won't hurt.

My 1965 owner's manual states that 10W-30 and 20W-40 are suitable for +32°F temperatures and I run 10W-30 in my slant six. I also have an hemi oil-spring in my engine and my oil pressure with 15W-40 is always 70 psi, which is excessive. Excessively thick oils cause the relief valve to divert flow to the sump instead of the bearings. See Engine Wear and Chrysler Oil Recommendations.

I would look for a dual-rated oil (eg, API CK-4/SN) with a Ford WSS-M2C171-F1 rating (1000-1200 ppm phosphorus) and the only one I'm aware of now is Petro-Canada Duron SHP 10W-30.
 
Ford Super Heavyduty 10W-30 meets FORD WSS-M2C171-F1
Pretty readily available. One of the better options available for a relatively high ZDDP package in a conventional oil. Plenty for stock engine, stock spring presures. etc. Probably group II base oil. No API cert, and obviously they won't recommend it for cars with cats due to the potential long term warrenty issues.
PETROLEUM QUALITY INSTITUTE OF AMERICA TEST PROGRAM-Ford Superduty 10W-30
 
I run Valvoline VR1 10W30 in my 170 . In summer I thicken it up with 2 qts of 20/50 same brand and also VR1 Racing . It has ZINK ! You need Zink for those solid lifters.
 
Assuming your car does not have a cat converter, I'd use SAE spec SG or SH motor oil, it has more zinc in it. SN has very little. Try looking at the labels on 'high mileage' oils.

As stated, 10w30 in the winter; 20w50 in the summer.
 
Mixing in some 20w50 will bring the viscosity up a reasonable amount for engines that run hotter in the summer.
Switching from 10w30 to a 20w50 is a huge jump in viscosity and would not normally be needed. If the engine is that loose, or bearings that worn, then a 10w-40 in the winter is probably a better match.

If we focus on the oil viscosity when the engine is warmed up, for normal driving its temperature going to be in the same ballpark as the coolant and most of the block.

So lets say in winter that oil runs 180 to 212* F
Using Brad Penn 10w-30 as an example, those temperatures put the oil viscosity between 17 and 11 centiStoke.
upload_2020-1-29_10-37-27.png


If summertime oil temperatures are 195 to 220*F, then oil viscosity will range from 14 to 10 centiStoke.
Therefore if the viscosity that provides the best flow and bearing support is in the 10 to 18 centiStoke range, then 10W-30 will be fine all year around.
If we observe that in hot conditions the oil pressure is noticible lower, then mixing in some 20w-50 or switching to 10w-40 makes sense.
But the oil temps would have to be running much hotter before switching to 20w-50; Looking at the graph Brad's 20w-50 drops to 18 cSt around 220*F and does go below 10 cSt until 270* F.
 
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valiantwagonguy said:
I run Valvoline VR1 10W30 in my 170 . In summer I thicken it up with 2 qts of 20/50 same brand and also VR1 Racing . It has ZINK ! You need Zink for those solid lifters.
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ZDDP means Zinc DialkylDithioPhosphate. It is actually the Phosphorus component of ZDDP that provides the antiwear protection and more is not better. Phosphorus levels over 1400 ppm can lead to increased engine wear and levels over 2000 ppm can lead to camshaft spalling. For flat-tappet engines, the Corvair Oil Guide recommends using Heavy Duty Engine Oils rather than racing oils.
See Valvoline Racing Oil FAQ #2 and GM TechLink - Engine Oil Myths

pt70 said:
Assuming your car does not have a cat converter, I'd use SAE spec SG or SH motor oil, it has more zinc in it. SN has very little. Try looking at the labels on 'high mileage' oils.

As stated, 10w30 in the winter; 20w50 in the summer.
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You'll have to comb garage sales to find obsolete oils like API SG or SH. Modern oils have to meet much more stringent performance requirements in addition to meeting the same specs as those ancient oils. The only difference is that STARBURST (and resource conserving) oils have a 800 ppm maximum limit on phosphorus. Heavy Duty Engine Oils have a 1200 ppm maximum limit on phosphorus and the Ford WSS-M2C171-F1 specification requires 1000-1200 ppm of phosphorus. See the API Motor Oil Guide:

For automotive gasoline engines, the latest ILSAC standard or API Service Category includes the performance properties of each earlier category and can be used to service older engines where earlier category oils were recommended.​


Mattax said:
Mixing in some 20w50 will bring the viscosity up a reasonable amount for engines that run hotter in the summer.
Switching from 10w30 to a 20w50 is a huge jump in viscosity and would not normally be needed. If the engine is that loose, or bearings that worn, then a 10w-40 in the winter is probably a better match.
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Mattax is correct. Excessive viscosity is not beneficial and it better to use an oil that has hot viscosity that doesn't raise the oil pressure to the point where the relief valve bypasses oil flow back to the sump. If you need the viscosity of a 40-grade oil, I would go with a dual rated (ie, API CK-4/SN) oil that also meets Ford WSS-M2C171-F1 like Petro-Canada Duron HP 15W-40.

If you're really concerned about your bearings, read about temporary shear in the Corvair Oil Guide. Look for oils with higher HTHS Viscosity and HDEOs generally have greater HTHS than Starburst oils.
 
This is a worthless topic to continue as the OP hasn't been seen or heard from since Sep 26, 2018.
 
It's a Slant Six ! Hell,they will run on anything and keep going just like the energizer bunny. We've seen them all run without ANY oil.:poke:
 
SH rated motor oil is still available from Kohler. It is oil used in their small air cooled engines. The recommended oil and filter change is 100 hours. 100 hours x 60 mph = 6000 miles.

Decades ago I used Amoco Superblend 10w30 in the winter. Changed to their straight 30 weight in the summer. Gained about 10 psi at hot idle. Even so, when draining the oil after a long drive in the summer [30 wt], it came out like a cow pissing on a flat rock.

This does not apply to newer engines. My 2.4 na calls for 5w30. That's all it gets. And after 100,000 miles, it sounds like a new engine.
 
pt70 said:
Even so, when draining the oil after a long drive in the summer [30 wt], it came out like a cow pissing on a flat rock.
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yep. Once the oil is up over 180* F there's only a little difference between 0w-30, 10w-30, straight 30 viscosity.
A conventional straight 30 will probably hold up a little better under shear and other properties. This was probably one of the reasons straight weights were used for long periods of hard running.

This is from Widman's oil overview. You can see how close a typical 30 and a typical 10w-30 are.

upload_2020-2-2_11-29-35.png

The 'zone of protection' is his description of the target operating viscosity for the air cooled Corvair flat six. Based on the oil grades recommended by Chrysler, its likely the acceptable viscosity range for our sixes and eights, was a little wider. Maybe as high as 18 or 20 cStoke.
 
Knowing the Chrysler recommended 30 only for summer use in many of our engines, lets say the target viscosity range extends up to 17 or 18 cSt. In that case we can see the 10w-30 is more likely to be in the target range, even in the winter. It will also get to that viscosity sooner, which is good for short trip and short drive situations.
upload_2020-2-2_11-52-35.png
 
pishta said:
All-Fleet Plus 10W-30 Valvoline
Napa Value 10W-30
Rotella T4 Triple Protection 10W-30
Rotella® T5 Synthetic Blend SAE 10W-30

hundreds meet that spec here...
https://parts.ford.com/content/dam/...iesel_Motor_Oils_Meeting_Ford_WSSM2c171F1.pdf
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Gotta remember the oil recommended in 65 was what was available in 65. There are better oils out there. And I would recommend not breaking in an iron ring motor with synthetic oil. Newer cars have much finer cylinder finishes and moly rings that do not require long break in times so they come equipped with synthetics from the factory.
 
pishta said:
All-Fleet Plus 10W-30 Valvoline
Napa Value 10W-30
Rotella T4 Triple Protection 10W-30
Rotella® T5 Synthetic Blend SAE 10W-30

hundreds meet that spec here...
https://parts.ford.com/content/dam/...iesel_Motor_Oils_Meeting_Ford_WSSM2c171F1.pdf
Click to expand...

What I said was: very few 30-grade DUAL RATED (API CK-4/SN) heavy duty oils also meet Ford WSS-M2C171-F1. Oils approved for API SN (Starburst or not) requires 600-800 ppm of phosphorus for 16, 20, & 30 grade oils while thicker oils (40, 50, 60-grade) only have 600 ppm lower limit. All single rated (API CK-4) heavy duty oils (including 30-grade) have 1200 ppm phosphorus upper limit and no lower limit, which is why Ford developed their own 1000-1200 ppm spec. See API: Latest Oil Classifications
 
So 10-30 weight is about equal to 30 straight? I've been using 30 straight but harder to come by. Considering VR-1 10-30 or brad penn 10-30. I went off my old mopar manual specific to my 1975 dodge dart sport 360.
 
A multi-grade oil (like 10W-30) means that it has the flow of a 10W-grade oil when cold and the flow of a 30-grade oil at 100°C/212°F. A single grade oil (like SAE 30) will be thicker (more viscous) than a multi-grade when colder than 100°C and will be thinner (less viscous) when hotter than 100°C. That is, a multi-grade oil has a flatter viscosity curve than a single grade oil.
 
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