Any thoughts on ACD & HDD

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653
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TX & ON
Hi, new here. Pros/cons of HDD or ACD on the first 2 vehicles in my signature vs AMO ? They will be operated in -40 to 110 or so, mixed city/highway, everyday. User experiences and balanced views please, not interested in stirring up an oil war on my first post. Regards.
 

JHZR2

Staff member
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46,137
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New Jersey
Amo is 10w-40, hdd is 5w-30 and acd is 30w/10w-30. I'm not seeing a compelling reason to select a 10w-40. HDD will have some obvious advantages in the cold over ACD, so I'd probably go that route. I have and use ACD for other stuff,and would consider it, if it weren't for the -40 temperature part.
 

ofelas

Thread starter
Messages
653
Location
TX & ON
AMO gives me about 20psi hot idle and I've used it in -40, though it was definitely happier at -20. T6 would not give me more than 12psi at hot idle. Both flow well enough to the valvetrain, but there's no compelling price difference between the two in Canada. The above values on the first vehicle - no fuel dilution issues btw. I hear ACD and HDD are thick 30w oils - any thoughts on which would give me higher oil pressure at hot idle ?
Originally Posted By: JHZR2
Amo is 10w-40, hdd is 5w-30 and acd is 30w/10w-30. I'm not seeing a compelling reason to select a 10w-40. HDD will have some obvious advantages in the cold over ACD, so I'd probably go that route. I have and use ACD for other stuff,and would consider it, if it weren't for the -40 temperature part.
 

ofelas

Thread starter
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653
Location
TX & ON
Originally Posted By: dnewton3
What are your OCI goals? Anything other than temp extremes to ponder? Price threshold?
Not a particular concern, as I have a couple gallons of HDD & ACD handy.
 

ofelas

Thread starter
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653
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TX & ON
I reckoned you'd provide some input based on your propensity for 10w-30 oil dnewton; don't be churlish. Thought the resident Amsoil dealer would chime in as well. Alright, let's narrow it down to AMO vs HDD for the '81 pushrod v8 in -40 to +100; mixed daily driving, average bearing clearances and the odd 2000lb critter in the bed while in four low.
Quote:
You already own them; use what you want.
 
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1,095
Location
Northern, NY
HDD will outperform in the extreme cold, and also has a higher viscosity at operating temperature. How often will your vehicles see the frigid temperatures? At -40 you would see the benfits of synthetic fluids in every compartment (power steering, transmission, differential), as well as block/pan heaters.
 

ofelas

Thread starter
Messages
653
Location
TX & ON
You meant HDD would have higher operating vis than ACD (not AMO) correct? The two first gen Dodge trucks see the cold; all synthetic in the tranny, transfer case, diffs, steering and grease. -40 may happen a couple times a week within a 2 month period, but it's -20 or so most of the winter. Would it still be worth going to HDD from AMO given hot summers as well, and yearly oil changes?
 
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8,051
Location
Michigan
If it's getting down to -40 a couple of times a week for a two-month period, you should be running a 0W-something to ensure good cold flow in that extreme condition. Then change to something thicker when the warm weather comes.
 
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176
Location
Woodbury, MN
Seems like the HDD would be the best choice year round in both cold and hot extremes. The HDD could handle both. The ACD is certainly a stout oil, but -40 is just too cold for it. Heck I think Amsoil lists the ACD cold flow at -37. If you have both, give them a try and see what you think is best.
 

ofelas

Thread starter
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653
Location
TX & ON
Will do powerstroke. The AMO in my sump is rated pretty decent for cold flow as well, but will see how the HDD does. Hopefully the HDD has decent operating temp viscosity for year round usage. Any thoughts on ZRT ?
Originally Posted By: Powerstroke
Seems like the HDD would be the best choice year round in both cold and hot extremes. The HDD could handle both. The ACD is certainly a stout oil, but -40 is just too cold for it. Heck I think Amsoil lists the ACD cold flow at -37. If you have both, give them a try and see what you think is best.
 
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