Comparing 30wt with 5W-30

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No, because as already noted pumpability at very low temperatures is influenced by shear in the oil around the pump inlet. Tom's post describes this. Pour point was demonstrated to be an unreliable indicator of pumpability at low temperatures.
I reference the pour point all the time. For example the 80w140 gear lube I use shows a PP of -33C, but 80W is a test conducted at -26C.
My gear lube won't pass 75W, but I'll bet the channel point is very close to the pour point and OK for use down to -33C.
How does that cross over to engine oil? Down to the PP, the oil should flow into the pump.
Back in the day before W grade tests were established, the PP was the benchmark for cold temperature performance.
 
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I reference the pour point all the time. For example the 80w140 gear lube I use shows a PP of -33C, but 80W is a test conducted at -26C.
My gear lube won't pass 75W, but I'll bet the channel point is very close to the pour point and OK for use down to -33C.
How does that cross over to engine oil? Down to the PP, the oil should flow into the pump.
Back in the day before W grade tests were established, the PP was the benchmark for cold temperature performance.
Definitely. But some engine failures in the 80s showed that it was unreliable. Even though the oil should have been pumpable it was not because when placed under shear at the pump inlet it would cause cavitation, as noted above.

And gearcase applications are different than for pumped engine oil.
 

OVERKILL

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Definitely. But some engine failures in the 80s showed that it was unreliable. Even though the oil should have been pumpable it was not because when placed under shear at the pump inlet it would cause cavitation, as noted above.

And gearcase applications are different than for pumped engine oil.
Yup, exactly, that's why specific tests (CCS and MRV) were developed.
 
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For a multi grade you look at the MRV and CCS data. That kv40 10cSt is significant - that's 100 deg F

Where an API designated product, If VM are employed, Mfg must label the product as a 10W or 5W if it meets fits below the upper spec margin for that winter rating

I am running a 10W30 in a 5W20 spec engine with better than factory results; it has a pour point of -54 degC.
Quaker State Full Synthetic - If you are thinking of a "more robust oil" I would recommend this product highly.

- Ken
Using a 10w30 in a 5w20!!!!! Oh the humanity by some. My car spec's a 0w20 and run a 0 or 5w30 and have had great results. Thanks Ken!
 

ZeeOSix

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Definitely. But some engine failures in the 80s showed that it was unreliable. Even though the oil should have been pumpable it was not because when placed under shear at the pump inlet it would cause cavitation, as noted above.

And gearcase applications are different than for pumped engine oil.
Yup, exactly, that's why specific tests (CCS and MRV) were developed.

Source: https://www.jstor.org/stable/44467123

Abstract:

SAE 841388 Abstract.JPG
 
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Yup, exactly, that's why specific tests (CCS and MRV) were developed.
Other than in a gear application where channel point is important, I wouldn't subtitute knowing the PP for the W grade.
To be safe, I like to be at least a grade below expected ambient. I've noted zero oil pressure with 5Wxx when company trucks were parked overnight in Hinton, Alberta at or around -35C. Some guys left their Diesel engines running all night in the hotel parking lot.
At those temperatures, it's not just the trucks and other machinery that has trouble getting going in the morning.... it's me.
Notice how MRV is always a grade or two below CCS? The theory is if it will start, the oil better pump.
Well, the 2017 GMC 6.0L started, but should have had 0Wxx instead of a fast lube place syn blend 5w30.
 

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Other than in a gear application where channel point is important, I wouldn't subtitute knowing the PP for the W grade.
To be safe, I like to be at least a grade below expected ambient. I've noted zero oil pressure with 5Wxx when company trucks were parked overnight in Hinton, Alberta at or around -35C. Some guys left their Diesel engines running all night in the hotel parking lot.
At those temperatures, it's not just the trucks and other machinery that has trouble getting going in the morning.... it's me.
Notice how MRV is always a grade or two below CCS? The theory is if it will start, the oil better pump.
Well, the 2017 GMC 6.0L started, but should have had 0Wxx instead of a fast lube place syn blend 5w30.
I think the PP is good to know yes, I typically err on the side of caution with the Winter rating for a similar reason as you. As we know, an oil is allowed to slip a Winter rating in service, and that does open the door for problems!

I've recounted this story before, but when we were driving back from my parent's place down east we stopped overnight in Quebec. It went below -30C that night and in the AM I didn't think the Expedition was going to start (the diesel beside us didn't start, they had to bring a big trailer in to get it going, not sure of everything they did, I assume block heater + boost). It was an honest -30C, no wind, I had Pennzoil Ultra 5w-30 in the sump instead of my usual Mobil 1 0w-30 and it rolled over so slowly I was sure it wasn't going to go. It did eventually catch and made all kinds of exciting noises for an uncomfortable amount of time. That was the last time that truck saw a 5w-30.

This is part of the reason I'm big into the PAO-based 0w-xx lubes in my own vehicles. Our RAM fired-off without even a hint of rolling over slowly when it was -30C this past winter with the EP 0w-20 in it, same with the SRT with the Ravenol. It makes a difference.
 

ZeeOSix

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Notice how MRV is always a grade or two below CCS? The theory is if it will start, the oil better pump.
Because MRV is an indication on how the oil will flow under its own weight due to gravity, and be able to flow to the oil pump pick-up. The oil's ability to flow to the pump pick-up is the critical aspect of a super cold start-up. If it can't flow to the pump pick-up, it doesn't matter how well the pump can move it. No oil supply to the pump pick-up means no lubrication going to the oiling system. Boom, smoked motor.
 
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Actually the MRV measures the drag via the Rotor to wall clearance in the test cell. The weight and associated string wrapped around the rotor shaft is routed over an encoder to allow the measurement of the rate of decent with that known weight.

This is one of the things we will be explaining at our upcoming open house.

David
 

ZeeOSix

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The goal of the MRV test is to determine the pumpability at very cold temperatures. Somewhere along the line, the people who have come up with the MRV apparatus and test procedure have equated the test measurements to the winter pumpability of oil (defined as a viscosity limit of 60,000 cP or less) used in engines the field. It was field failures in very cold weather that basically called for a pumpability standard and measurement to be created and expressed in SAE J300.


 
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I think the PP is good to know yes, I typically err on the side of caution with the Winter rating for a similar reason as you. As we know, an oil is allowed to slip a Winter rating in service, and that does open the door for problems!

I've recounted this story before, but when we were driving back from my parent's place down east we stopped overnight in Quebec. It went below -30C that night and in the AM I didn't think the Expedition was going to start (the diesel beside us didn't start, they had to bring a big trailer in to get it going, not sure of everything they did, I assume block heater + boost). It was an honest -30C, no wind, I had Pennzoil Ultra 5w-30 in the sump instead of my usual Mobil 1 0w-30 and it rolled over so slowly I was sure it wasn't going to go. It did eventually catch and made all kinds of exciting noises for an uncomfortable amount of time. That was the last time that truck saw a 5w-30.

This is part of the reason I'm big into the PAO-based 0w-xx lubes in my own vehicles. Our RAM fired-off without even a hint of rolling over slowly when it was -30C this past winter with the EP 0w-20 in it, same with the SRT with the Ravenol. It makes a difference.
When my daughter was in undergraduate school in northern Wisconsin there are times when she started my/her old 1994 BMW 530 in -30F temperatures. You are correct that there are can be all sorts of protest noises from the engine at those temperatures. It’s not for the faint at heart especially with a ~25 year-old car. I always told her to let it warm up before proceeding and to make the trip count.
 
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