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What oil are you using.


frijolito
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27 minutes ago, Sniper said:

There is no ML grade oil anymore, unless you find something on a shelf in someone's garage.  That is a system that they replaced in 1981 with what we are using today.

 

SAE 10 is 10W, https://www.sizes.com/materials/engineOil.htm

The W only means it's a winter grade.  No one was specifying 10W for summer use, only winter, which is why the W was appended.  Has nothing to do with the advent of multi-viscosity oil.

 

Multi-viscosity oils have nothing to do with polymer coated bearings and everything to do with how thick the oil is at a specified oil temperature.  Straight 30 weight oil is very slow to pump in cold weather.  So thinner oils were specified for those climates.  Do a test.  Get a bottle of 30 and a bottle of 10w30, put them in the freezer overnight.  Next morning pour them out and see which flows quicker.  At those temps the 10w30 flows like a 10W oil, as it heat sup to operating temp is thickens up to a 30 oil.  That is all multi-viscosity oil means.

 

I bet Chrysler recommended straight 10w break in oil because straight 30w is too thick for .0005 factory recommended clearance (many of us run .001 - .002) and thats all they had before 10w 30 became the norm in the mid 50's.  But they also said to not drive the motor at high speeds during the break in either, which could have been because of thin 10w oil... 

 

For my new rebuilt motor I used 10w 30 as a break in oil and the rings seated just fine.  No way in hell I would risk my bearings with straight 10w.

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this has been a good topic. 10/30 has alway been my drink of choice. But now (thanks to this discussion) Im rethinkinking

oil choice. Booger doesnt play in the snow..-10 F (no) and freeway speed often surpass 3000K rpmz. (yes). So 40 weight

(which was a standard way back when) seems to be a logical choice. Is a 20w-50 oil too tricked out for flatties?

Flatties not fattys. ( your honor I am guilty as charged)

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The best choice is the thinnest oil you can run that gives you acceptable oil pressure.  Anything thicker is just wasting horsepower and fuel.  I don't recall Chrysler recommending 40 weight oil, 30 has been the standard.  Now if your engine is worn and bearing clearances have opened up 40 might help get your oil pressure up, but it's a band aid.

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A few have mentioned zinc phosphate content, and if our cars with mild valve springs ' need' it.

I would argue that it IS need, IF you are starting a newly built engine where there cam and lifters (flat tappet) are new or reground. 

Is it possible that it is overkill? Sure, but it is so cheap compared to a new engine that I will risk the minor waste of $$.

I like oils with their own zinc, vs additives.

Amsoil offers a dedicated "break in oil" 30 weight, with high zinc and no friction modifiers. 

They also offer "Z-Rod" oil in various weights for general classic car use. 

It is not hard for me to believe that modern oil is tailored for modern engines. What engine has been built in the last 10+ years that hasn't had EFI, roller lifters, low friction design, pcv systems, etc?

 

I know that my car is fairly sludged up, so I am pulling the valve covers and oil pan to manually remove deposits before running modern oil. I will change the oil and filter at 500 miles, and again at the next 1000 miles. The I will start running something like the Z-Rod oil.

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33 minutes ago, FarmerJon said:

A few have mentioned zinc phosphate content, and if our cars with mild valve springs ' need' it.

I would argue that it IS need, IF you are starting a newly built engine where there cam and lifters (flat tappet) are new or reground. 

Is it possible that it is overkill? Sure, but it is so cheap compared to a new engine that I will risk the minor waste of $$.

I like oils with their own zinc, vs additives.

Amsoil offers a dedicated "break in oil" 30 weight, with high zinc and no friction modifiers. 

They also offer "Z-Rod" oil in various weights for general classic car use. 

It is not hard for me to believe that modern oil is tailored for modern engines. What engine has been built in the last 10+ years that hasn't had EFI, roller lifters, low friction design, pcv systems, etc?

 

I know that my car is fairly sludged up, so I am pulling the valve covers and oil pan to manually remove deposits before running modern oil. I will change the oil and filter at 500 miles, and again at the next 1000 miles. The I will start running something like the Z-Rod oil.

 

All this discussion about viscosity and break-in in the end have to do with oil thickness coating at various RPMs.

 

Found this really technical paper online that relates oil film thickness, power loss, oil pressure to viscosity at differing rpms

 

I haven't really digested it all, but it should inform this discussion.

 

https://www.substech.com/dokuwiki/doku.php?id=effect_of_oil_viscosity_on_hydrodynamic_friction_of_engine_bearings

 

image.png.890543860a26fb72dcf164e716c60a6a.png

 

image.png.2b2f55578eb25785f6ce013cdb748bad.png

 

image.png.d9050a5413602f7a294dc3bee020faf0.png

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I've always like Castrol GTX, they now have a "Classic" version with more zinc content. The extra zinc may not be needed in our old Mopars but I also use it in the TR6 that has a new cam and lifters. Castrol GTX Classic 20W-50 is available at Walmart and Amazon:

 

51el8DIoUIS._AC_UL116_SR116,116_.jpg

 

P.S. Not recommended for cars with catalytic converters.

Edited by Sam Buchanan
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