Quote:
Originally Posted by M.D. Holloway
While it is possible for engine oil to shear down, I have seen it mostly when oil blenders try to achieve a 0W30 or 0W40. Normally you can't get that sort of a cold crank viscosity and a high operating viscosity without the use of viscosity index improvers and thats what will shear under harsh conditions. They are polymers that are not always shear resistant compared to the base oil which is a polymer but is far more shear resistant. defing harsh conditions? Now harsh conditions may bring up images of the Oil Sands in January or the Mojave desert in June. But actually how folks start their engines can have just as much damage. Contamination can do it as well.
Blackstone is a funny lab. They tend to paint various problems with a very broad brush. They are not at all active in STLE or ICML compared to other labs which is a red flag. They don't have the confidence of the major oil companies because they tend to simplify conditions and blame the oil. Frankly, only about 5% of any failure can be traced to the oil. If fact its most likely less then that.
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So what I gather from this:
1)- shear is not by design, but a fault.
2)- Blackstone oversimplifies matters.
Next question: If oil is discovered as sheared- IE 5/30 to 20WT- does that mean change oil time?
rjp