Synthetic or Conventional motor oil in Kubota diesels

TheOldHokie

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I believe it's 10w30 in my manual.
Or alternatively SAE 20 in my manual, Good luck finding an SAE 20 CK4 heavy duty diesel engine oil :devilish:

I think we got sidetracked with the conventional vs. synthetic debate when the original concern (at least for me) was really 5W40 vs 15W40. I live right on the Mason Dixon line and we still get single digit temps. An SAE 15W40 is simply not a good choice for all season use here. If you want to run a grade 40 all year round a 5W40 or 10W40 oil is a far better choice. Your choices for a conventional CK4 diesel oil in those grades is going to be limited. to say the least. Possibly in 10W40 but I seriously doubt anyone makes a conventional 5W40,

Dan
 
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RalphVa

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Or alternatively SAE 20 in my manual, Good luck finding an SAE 20 CK4 heavy duty diesel engine oil :devilish:

I think we got sidetracked with the conventional vs. synthetic debate when the original concern (at least for me) was really 5W40 vs 15W40. I live right on the Mason Dixon line and we still get single digit temps. An SAE 15W40 is simply not a good choice for all season use here. If you want to run a grade 40 all year round a 5W40 or 10W40 oil is a far better choice. Your choices for a conventional CK4 diesel oil in those grades is going to be limited. to say the least. Possibly in 10W40 but I seriously doubt anyone makes a conventional 5W40,

Dan
According to my calcs, a 10w40 would crank at 160 rpm if a 15w40 cranks at 100 rpm (barely fast enough to start), almost as fast as 170 rpm a 10w30 would crank at. By comparison, a 0w30 would crank at 200 rpm, which is probably more than most starters are able to do, even in summer.
 

TheOldHokie

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According to my calcs, a 10w40 would crank at 160 rpm if a 15w40 cranks at 100 rpm (barely fast enough to start), almost as fast as 170 rpm a 10w30 would crank at. By comparison, a 0w30 would crank at 200 rpm, which is probably more than most starters are able to do, even in summer.
I think we are in fundamental agreement although my concerns are less about cranking speed and more about cold oil flow to the upper end and cylinder walls.

Dan
 

RalphVa

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I think we are in fundamental agreement although my concerns are less about cranking speed and more about cold oil flow to the upper end and cylinder walls.

Dan
Lower first digit oil will get it pumping up there quicker, 0wxx probably almost instantaneous even at -40 F/C.
 
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RCW

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I know I’ve mentioned this before; first winter I used 15w-40. Upstate New York. Cold starts were rough.

5w-40 T6 is much nicer….
 

DustyRusty

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I use a block heater on my tractor when the temps drop to 20 above zero, and my tractor has always started. My 4 cylinder Lister Petter diesel has 15-40 full synthetic in it, and when the power goes out it automatically starts. It has a heater in the intake manifold and glow plugs. If I am anticipating a power outage because of a storm, I have a block heater that I keep plugged in, until the storm passes.
 

TheOldHokie

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Do they sell 5w Conventional diesel oil? I’ve never seen it for sale.
I would be very surprised if they did. I looked and could not even find a conventional 10W40 for anything other than passenger cars. I found a few semi diesel oils in that grade. Why would a company even try to formulate them when synthetics are so easy to make?

Dan
 
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DustyRusty

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I would be very surprised if they did. I looked and could not even find a conventional 10W40 for anything other than passenger cars. I found a few semi diesel oils in that grade. Why would a company even try to formulate them when synthetics are so easy to make?

Dan
Because someone in the marketing department is reading this thread and wants to prove that they can be everything to everyone! :)
 

Brins

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As Castrol touted during the 80’s “Oils aint Oil’s,

I didn’t take Castrol’s advice to use their product in that instance, but focused in on Mobil 1.

I got caught up in the Synthetic hype, Mobil said it was the best, it was the most expensive oil off the shelf and I believed every word of it.

When it came around to the D1005 I wanted to give it its best chance for long life.

Its 18 years running now and still putting along well.
 

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VW sells it from their parts department: 5w30 Castrol "synthetic" (probably Group III).

I get 0w30 M1 ESP at Advance Auto.
I’m all for synthetics. I was just replying to the comment that the comparison wasn’t valid: 15w conventional vs 5w synthetic for cold weather. If you want 0 or 5w oil, synthetic is the only option.
 

TheOldHokie

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VW sells it from their parts department: 5w30 Castrol "synthetic" (probably Group III).

I get 0w30 M1 ESP at Advance Auto.
He was asking about a conventional 5W-xx Ralph.
I’m all for synthetics. I was just replying to the comment that the comparison wasn’t valid: 15w conventional vs 5w synthetic for cold weather. If you want 0 or 5w oil, synthetic is the only option.
I’m all for synthetics. I was just replying to the comment that the comparison wasn’t valid: 15w conventional vs 5w synthetic for cold weather. If you want 0 or 5w oil, synthetic is the only option.
Almost exactly what I was trying to say.. Let me try once more to phrase it more clearly:

"If you want a grade 40 oil for year round use in cold (15F and below) weather synthetic is the only thing available with the viscosity spread needed."

Kubota does not recommend a grade 15W40 of any type for use below 15F,

Dan
 
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bbxlr8

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So... in backing up the above - I just did my 50H and went to T6 5W-40.

VERY noticeable difference in first starts even when temp's here have not been that that cold recently
 

top gnome

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I am having trouble finding rottella 5w40 is it ok to mix with 0w40? 2 jugs is 3 oil changes so I would like to buy 2 jugs but CT only has one of each thank you

Ben
 

Pau7220

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I am having trouble finding rottella 5w40 is it ok to mix with 0w40?
As long as it is diesel certified you’ll be fine. A different brand of 5w-40 full synthetic (valvoline, mobil 1, etc.) will be fine also.
 
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