evil MS3

So according to the analysis, everything is great with the oil/motor. The only thing they noted was that the oil viscosity was below spec and was in the 5w30 area. The oil I ran during this time was Castrol Syntec 10w30. They note that considering the normal wear that this isnt a concern.

So, what caused the loss of viscosity? Should I stick with the same oil?

zeroptzero

For some reason this vehicle does shear down many oils, this is very normal for this engine. My 5w40 sheared down to a thick 30 weight as an example.

Your oil did shear down but I wouldn't say it affected your wear at all. It is actually a thick 20 weight oil at that viscosity, a little bit off the lower end of the 30 weight spectrum. We don't know the starting viscosity of this oil in virgin form, but it is safe to assume that it has sheared a bit. It was probably a good time to change the oil at that mileage, even thought it likely had enough additives to go longer (lack of TBN info though). I would keep it around the 5k mile mark if it was my engine, though the oil could certainly be used longer.

Conventional and Group 3 oils seem to be more prone to the shearing on these engines, there are some good high quality real synthetics that are more resistant to shearing, but all oils seem to shear down a little bit.

This is a good report though, wear metals are pretty low, and good filtration going on. Nothing to be concerned about. Thanks for positing this info.

evil MS3

sweet, thanks for the breakdown

SpitfireS

Hmm...
Oil does not shear down from a 10W-30 to a 5W-30.
That statement - coming from an oil lab - is.... I donno... stupid?
I mean, the tested viscosity is below the SAE 30 range, as spec'd in the SAE J300 spec.
(Google )
IOW: it sheared into a 20 weight.
That sounds scary but it isn't.
As JFUSION mentioned lots of oils shear down out of grade in the F20/F22 with no higher "wear", as shown in your report.

Lately, UOA's posted here were showing more shear stable oils, oils that stay in grade.
This is not one of them.

evil MS3

what are some of the shear stable oils you've seen posted? just for reference. Considering it doesnt sound like its anything to worry about considering wear remained normal, but I'd still like to know.

starchland

what air and oil filters are you using for this UOA?

Also, I have read that syntec 10w30 starts out as a very thin oil when compared to other 30s

zeroptzero

recent one we've seen was Amsoil 5w30.

CarbonCrew

Castrol lists kinematic vis. from Syntec 10w-30 at 100C as 10.1 cSt.

What I don't understand is Blackstone's range for SAE 30 weight, my copy of SAE J300 2009 lists SAE 30 as 9.3-12.5 cSt.

If you are looking for a more shear stable oil, look for those that are true synthetics (Amsoil, RLI, etc.) or have a higher concentration of PAO/Esters.

INDYMAC

As a good rule of thumb, energy conserving oils of the SAE 30 grade will shear quite a bit by design. That's how they get their energy conserving rating. It doesn't appear to be base oil content related. If you want an oil to stay in grade better, then use a PCMO that has not earned the energy conserving oil certificate or use an HDEO 30 or 40 grade with a SM/SL/CJ-4 (gas or diesel) rating.

This Castrol Syntec UOA seems to show that you are probably conserving energy and controlling wear very well. Very impressive! Thanks for posting.

CarbonCrew

As synthetics are generally characterized by higher shear strengths, API's Energy conserving ratings has got to be base oil content related. I think base oil content has a lot to do with the reason we have yet to see many synthetics (5w-30, 0w-30), if any at all, carry API's SM or SN ratings.