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Discussion Starter · #1 ·
I have a 2004 Ram 1500 4x4 with 5.7L V8 (HEMI). The manual says the preferred oil weight is 5W30. What is the defference between 5W30 vs 10W30? Also, would I harm the motor by using 10W30? I live in the Midwest (St Louis) so we have hot/humid summers and cold winters. I occassionaly tow and light Aluminum hull bass boat as well. I mainly drive highway miles.
 

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The first prefix 5, or 10, is what the oil will flow in the wintertime. The second is summertime. I would stick with 5w30, it is fluid enough to flow in the cold winters, yet it will hold it's viscosity in the summer too!
 

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New manual and specs for 2005 hemi is now 5W20
 

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Discussion Starter · #4 ·
5W20? Is that for the 05 HEMI? I believe some Ford motors in their trucks use this weight oil.
 

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Where do you live. I'm in Louisiana and always run 10w30. Ford does recommend 5w20, thats what goes in my wifes V6. If you are in the south, running most of the year at 70+, run 10w30.
 

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5W20 is for the 2005 hemi and I would assume for all hemis

This is a new spec that just came out
 

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I would never run 5w oil anywhere south of the north south divide. Man its 98 outside today........5 weight, and pulling something, you are asking for it......
 

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Discussion Starter · #8 ·
I live in St Louis MO. We do have warm summers (temps over 95-100degrees) but also have cold winters (avg about 25-30degrees but sometimes in the negative numbers with windchills). I really don't want to switch back and forth between 5W and 10W during the different seasons.
 

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spharis said:
I would never run 5w oil anywhere south of the north south divide. Man its 98 outside today........5 weight, and pulling something, you are asking for it......
As far as I know Dodge hasn't put out separate specs for the North and South

I assume they know their trucks are sold in Texas Florida Nevada etc
 

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C HEMI GO
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sugelle said:
I have a 2004 Ram 1500 4x4 with 5.7L V8 (HEMI). The manual says the preferred oil weight is 5W30. What is the defference between 5W30 vs 10W30? Also, would I harm the motor by using 10W30? I live in the Midwest (St Louis) so we have hot/humid summers and cold winters. I occassionaly tow and light Aluminum hull bass boat as well. I mainly drive highway miles.
I live in Tulsa and run 5w30 year round. My climate is about the same as yours.
 

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5w is the viscosity when the oil is cool, 30 is when it is warm(tested at 220 degrees, so the 30 is the main part) But that initial takeoff 5w is pretty thin stuff. Also, the oil weight is recommended, not set in stone. Run what you want, but you will never see me drop 5w in a V8 unless Im a canuck......

Reference chart from a maintanence manual follows.........I wouldnt run 5 weight south of the divide.......

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FYI....some quotes.....
The carmakers usually specify a 5W-20 or 5W-30 oil, particularly for lower temperatures, with a 10W-30 oil as optional, particularly for higher ambient temperatures.

Viscosity (a fluid's resistance to flow) is rated at 0° F (represented by the number preceding the "W" [for Winter]) and at 212° F (represented by the second number in the viscosity designation). So 10W-30 oil has less viscosity when cold and hot than does 20W-50. Motor oil thins as it heats and thickens as it cools. So, with the right additives to help it resist thinning too much, an oil can be rated for one viscosity when cold, another when hot. The more resistant it is to thinning, the higher the second number (10W-40 versus 10W-30, for example) and that's good. Within reason, thicker oil generally seals better and maintains a better film of lubrication between moving parts.

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So whats all this mean.......if it is 90+ outside, your engine oil is already around 20w if you are running 5w.....but if you are running 10w, you are around 15......which means you actually have better oil viscosity at a warmer climate.
 

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I've been using Valvoline Durablend 5w-20 in my '05. I just bought 7 quarts of 10w-30 Durablend. I've been reading good reports with used oil analysis with 5w-20 but I just can't get used to it. I'll be going to full synthetic next change. I might use 5w-30 but it's really pointless in the south. We never see below 30*F and that's very rare. The only reason for 5w-20 is for CAFE requirements. I like better mileage as well as anybody but towing over 10k lbs in Florida heat needs good oil protection better than 2% better mileage.
The first number is the base oil's viscosity. The second number is the viscosity the oil resembles at running temperature. Additives are used as thickening agents to acheive the second number. The closer the numbers the better. I'm not an oil scientist but there's plenty of reading over at,

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=forum;f=1

I also sent an email to my favorite API certified oil manufacturer. They concured the 5w-20 is for CAFE and 10w-30 will be fine for my Hemi. Not recommending, just giving my $.02 and what I'll be doing...
 

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Use a good 5W synthetic (your choice) in your Hemi
and you will have no problems anywhere in the USA. I
know that the 05 Hemi now calls for a 20 weight oil.
I would never use that in a V8. The only reason
Chrysler is using 5W-20 is to meet new CAFE standards.
For the sake of 1/2mpg improvement I would not use
that oil if I lived in hot climates.
 

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spharis said:
5w is the viscosity when the oil is cool, 30 is when it is warm(tested at 220 degrees, so the 30 is the main part) But that initial takeoff 5w is pretty thin stuff. Also, the oil weight is recommended, not set in stone. Run what you want, but you will never see me drop 5w in a V8 unless Im a canuck......

Reference chart from a maintanence manual follows.........I wouldnt run 5 weight south of the divide.......

-----------------------------------------------------------------

FYI....some quotes.....
The carmakers usually specify a 5W-20 or 5W-30 oil, particularly for lower temperatures, with a 10W-30 oil as optional, particularly for higher ambient temperatures.

Viscosity (a fluid's resistance to flow) is rated at 0° F (represented by the number preceding the "W" [for Winter]) and at 212° F (represented by the second number in the viscosity designation). So 10W-30 oil has less viscosity when cold and hot than does 20W-50. Motor oil thins as it heats and thickens as it cools. So, with the right additives to help it resist thinning too much, an oil can be rated for one viscosity when cold, another when hot. The more resistant it is to thinning, the higher the second number (10W-40 versus 10W-30, for example) and that's good. Within reason, thicker oil generally seals better and maintains a better film of lubrication between moving parts.

---------------------------------------------------------


So whats all this mean.......if it is 90+ outside, your engine oil is already around 20w if you are running 5w.....but if you are running 10w, you are around 15......which means you actually have better oil viscosity at a warmer climate.
Some minor corrections to this statement. If you are running 5w30, your oil is NEVER thicker than "5." If you are running 10W40, then it is never thicker than "10." The second number is more of a "what if" scenario. The second number is saying that the oilis low vicosity for easy startup and higher performance, but at high temps (220deg) it performs like a higher viscosity oil. 10w40 oil is like starting your car in the morning with SAE10 (SAE is constant grade oil) and running it at noon with SAE40. At 220degrees, the 40W oil has thinned to about a 4. So they take a 10W oil and add polymers that make it thin very slowly. An SAE40 oil might thin from 40 to 4 when it heats up 200degrees, but a 10w40 oil will thin from 10 to 4. Since this "modified" 10w oil is the same thickness at 220deg as the 40w is, it gets called 10w40.
 
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