I've had oil analysis done for the past two changes, both through Blackstone Labs. The first time I sent them Mobil 1 Full Synthetic 10W30 with about 4,000 miles on it. Apparently I didn't mark the "10W30" part on my form, and they just assumed it was 5W20 based on the viscosity it measured at. I asked them about it and they said it was "not uncommon" for these cars and didn't think anything was wrong with the oil or the motor. So I sent them another sample after my next oil change. This time I sent them a sample of Castrol Edge (Gold bottle) 10W30 and I made sure to include the "10W30" on the sample sheet. Keep in mind that this sample oil only had 500 miles on it. Sure enough, the analysis report comes back with "Castrol Edge Syntec 5W30" at the top of it, even showing that the viscosity was low for that weight. I'm beginning to wonder why my oil is shearing down so quickly. I'm also losing faith in Blackstone to perform an accurate analysis if they don't even properly use the information I give them with the oil sample.

Anyone else have similar experiences with ether oil shearing or Blackstone? Why would the oil shear so quickly?

 

Maybe switch to a 0w40

 

That doesn't really explain why my oil would be shearing so dramatically in the first place though. Just trying to find out how typical that is. Have you experienced this before?

 

The S2000 engines, trannies and diffs shear oils of all makes and viscosities very quickly based on the UOA's that I've done and seen. But Blackstone is only testing for kinematic viscosity, not HTHSv at 150C. HTHSv is the most protective aspect for an engine oil for bearings. There is a minimum centistoke at 150C for our cars, but I don't know what it is (2.6, 2.9, 3.0, 3.5?) So if you want to know what HTHS shear you have, you have to ask BS or maybe IOM to test it for you. According to API, a SN 30 grade should start with 2.9. And most of them do.

Why all the shearing? Viscosity index improvers (polymers) of poor quality, fuel dilution, mechanical shear from chains, gears and cams. It's also a formulator trick to help their product meet the strict energy conserving seal of approval.

But the best thing you can do is keep all your fluids new and fresh. You'll sleep well at night (unless you're Joey!)