Originally Posted By: bruce381
"Bruce, you thought wrong."
Says who?
stop Patronizing me
""If you have, you'd know that viscosity bounces down, and can even recover and bounce back up, if the VIIs are not permanently damaged, or are replentished.""
YES I have for many years and I have never SEEN an oil go down to 13 at short miles than back 15 it does not happen in my world unless you count oxidative thickening then I would agree.
Without an UOA we will never know, any any thing you or I say will only be a guess.
bruce
Bruce
I am not patronizing you. I was responding factually to your comment:
Quote:
"I thought this stuff did not have any aromatic or chemcial shear? Which is it?"
Your thinking is wrong. No one has every said that, to my knowledge. I certainly did not.
Here's an example of viscosity shear due to fuel and partial viscosity recovery that I was talking about. The oil used was Motul 0W-40
Miles .. Vis ... Fuel ... Oxidation
VOA .... 11.8 ........... 85
537 .... 11.9 .. 1.72% .. 76
1086 ... 12.4 .. 1.65% .. 78
1633 ... 11.6 .. 1.70% .. 78
2923 ... 9.9 ... 2.00% .. 101
Initially the viscosity of the oil in engine raises and stabilizes, then under continuous chemical/mechanical attack it crashes. The crash is easily recognized by the drop in viscosity (for this oil) and the spike in the oxidation measurement. Even though the oil is going through oxidation, it appears that the VIIs have been fatally damaged. This particular sequence was taken over the period of one trip with 90% highway driving. Had I run this for a longer period, it would have thickened back up, due to oxidation, and most likely ended up back near the starting grade.
Here's an example of an RS4 with Biosyn. 3/4 qt of the same batch was added between 1113 and 5065 miles.
Miles .. Vis ... Fuel ... Oxidation
VOA .... 16.1 ...0.35% .. 154
1113 ... 13.4 .. 1.55% .. 149
5065 ... 14.8 .. 1.03% .. 155
No significant oxidation change is recorded. Viscosity gets a boost, fuel is reduced and there are quite a few other indicators that the oil additive package has been replenished.
As for ChefWong's UOA, it is my opinion that BioSyn is cleaning his engine, and taking a huge hit because of it. There are some synergistic benefits of adding fresh oil to this after the early hit that it takes. It is clear in the oil samples I've taken with only 3/4 to 1 qt out of 10. I suspect that a larger synergistic effect occurs when 2 quarts are replaced.