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Engine Oil What Weight ?


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  • Staff

I run synthetic 15w-40 year round, if I ran dino oil and saw below 0° I would switch in winter. I have seen how slow dino 15w oils move below 0, it's not something I want in my engine. If I lived in areas that saw below -25° I would run synthetic 5w-40.

 

There are a few 30wt oils that meet the Cummins min high temp cST spec, Amsoil HDD comes to mind. But if you tow heavy or make a bit of HP I would stick to a 40wt.

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  • Owner

Still flowin' :lol:

 

post-1-0-23260100-1392922871_thumb.jpg

 

I have a hard time with the synthetic idea being all the local truckers (loggers and other wise) I running this same oil in their over the road trucks. I'm finding a very very small percentage of Over The Road truck even consider synthetic as a option. But weight wise I would adjust weights for long term exposure to minus temps. Like where I'm at I might see week or 2 weeks and pop back up again. Not worth losing sleep over it being once again these big over the road truck run the very same oil.

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The over the road trucks flow a ton more oil volume through their pumps though. Not to mention the general size of their oil filters and what not. You may not be cold enough to worry about it in Idaho but I noticed a big difference when I switched to the synthetic here. The truck starts and just generally runs easier. Its nice to have almost instant oil pressure vs. waiting 10 minutes just to get up to 40 psi.

Like I said before though, Idaho doesnt really get all that cold, even -20 isnt really all that cold IMHO.

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  • Staff

Sump size makes comparing OTR to our ISB difficult.

 

I am running dino on my new motor right now and there are some noticeable differences over synthetic. Dino takes longer to build pressure, and drops pressure with temp quicker. Synthetic is just more temperature stable.

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  • Staff

Here it is.

 

As I mentioned in the video the oils are Amsoil AME 15w-40 synthetic, Valvoline Premium Blue Conventional 15w-40, and Amsoil SSO 0w-30 gas engine oil.

 

Amsoil AME has a pour point of -44°F, and a CCS Viscosity @ -20°C of 4386.

Premium Blue has a pout point of -22°F and a CCS Viscosity @ -20°C of 6500.

Amsoil SSO has a pout point of -60°F

 

You can see why one shouldn't run conventional 15w-40 at temps much below -10°F without a block heater. At -5°F the conventional flows okay, and pump-ability will be better than flow but it still took nearly 3x as long to hit the bottom of the jar vs the AME.

 

th_IMG_11971.jpg

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  • 2 weeks later...

With the weather here (70 days this season starting out below zero) I am going to stick with synthetics too. Can you imagine what the gear oil is like when it gets real cold? The ring gear would just cut a groove until it started to warm up some.

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Not only gear lube but I have seen older equipment that still ran straight 30 weight oils yet where when the oil plug was pulled out on a cold engine in sub zero conditions the oil was like molasses and would'nt even come out of a 3/4 to 1 inch drain hole. :duh:

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