MolaKule
Staff member
Here are some interesting conclusions from an older paper on base oil viscosity and VII's:
Base Oil Viscoitiy and VII by Lubrizol India - HTHS and SSI
Base Oil Viscoitiy and VII by Lubrizol India - HTHS and SSI
Do you have some additional scientific information to include? Not sure what you are trying to convey.watching this thread agree with some of it some not so much
I wish I knew this thread was open when it was active. It's a good subject.Molakule,
we had some issues a few years ago with ISO460 gear oils rapidly becoming 200(ish) in service.
The manufacturer denied having Viscosity Modifiers in their ISO grades, pointing to the 98 VI...but within 3 months, no changes at our end on multiple pieces of equipment, the oil stopped breaking...three years later, it was back again...evidence of PIB (or similar thickeners)
Interesting I have done exact same thing with h-300 as well as PAO 100.I wish I knew this thread was open when it was active. It's a good subject.
Several years ago I was looking for low cost synthetic fluids or VMs (thickeners) for an ISO 680 gear oil. I formulated using a base fluid of 12% Indopol H300 (polybutene; KV100=605-655; VI=173) and bright stock (GI mineral oil; KV40=480). This would have yielded a VI of about 98-102. Long story short, I put the oil into a planetary swing transmission of an electric rope mining shovel, a high shear application. The oil began to loose viscosity within a few days and at 14 days it was down to about 525 KV40. I repeated this another time with the same result. Polybutene/PIB does not appear to be shear stable in geared system.
You can identify polybutene by infrared spectroscopy. Further, I wouldn't be surprised to see the VI drop as viscosity drops.
VMs, especially the VII type, are task specific. In other words, a VII developed for gears is stable in a geared system but not in an engine. Powersports engine oils with shared compartments are extremely damaging to many VIIs. A VII may be fine in separate compartments but when exposed to gears or a wet clutch loss viscosity immediately.