It appears from my data/trend line that I *may* see an increase in viscosity as my OCI increases past ~7K as the trend line appears to starts bending back upwards. I take from reading up on this that this is likely due to oxidation. Thoughts? You always need more data and I know this is a limited dataset.
Increase in viscosity with OCI - oxidation?
- Thread starter TiGeo
- Start date
That's the normal process of oxidative thickening. I wouldn't worry too much about what you're seeing there. As buster mentioned, oils that are less shear stable, typically from higher amounts of viscosity modifiers, will lose viscosity at first before oxidation begins to thicken it again.
I've also wanted to investigate if the evaporation of lighter components of the oil, those with lower viscosity and lower SpG, could be another reason viscosity increases with use. I feel this effect would be minimal in a normal, healthy engine that doesn't consume oil, but possibly a thought.
I've also wanted to investigate if the evaporation of lighter components of the oil, those with lower viscosity and lower SpG, could be another reason viscosity increases with use. I feel this effect would be minimal in a normal, healthy engine that doesn't consume oil, but possibly a thought.
My recent results with viscosity increasing from 12.2 to 13.9 seem to confirm the increase with time. See my 12k, two year run here:
0w-30 German Castrol EDGE SYTNEC SL - 12k OCI - 26 months - 2005 Vibe 1ZZ-FE
I'm not used to seeing so much TITANIUM 34, but I think that is a Castrol thing. I have never gone this long of OCI before (26 months and 12k miles) but it looks like the oil held up fine. However, you can see that cSt Viscosity has bumped up a bit into the 40w area. This first 10 months this...
bobistheoilguy.com
Similar threads
