Originally Posted By: DeepFriar
I am troubled by this new (to me) pressure viscosity coefficient metric. If indeed it shows a weakness in ester based oils it does not square with over 20 years of continuous hard use of Redline oils in the SE-R in the signature below. As some of you know I have described its use in various competitions and hard use up to this day. 225K of 242K miles has been "ester based oil" without so much as a spun bearing or any other need to have it apart. Hard use is putting it mildly with innumerable long stints into and out of the 6-8000rpm range and it is still repeatedly redlined in the local mountains at least once per week. I would find it unlikely anybody would say it's not seen extremely hard use.
Until I see some real world example that PVC has something other than theoretical merit with esters I will remain unconvinced. It may be that PVC is a distinction without a difference. I just don't know but if it's held everything together for a couple of hundred thousand miles then something about the PVC metric regarding esters is in doubt. I do wish the OP well with this change to a known exceptional oil. I expect good results although I too worry it may be a bit thin.
http://www.machinerylubrication.com/Read/586/viscosity-coefficient-bearing
Practical Guidance for Selecting Lubricant
(as demonstrated by Figure 3):
- PAG oils have significantly thicker films than PAO and mineral oils over the entire range of practical temperature.
- There is little difference between PAO and mineral oils for the temperature range of 70°C to 90°C. In this same temperature range, PAG lubricant gives 16 percent to 37 percent thicker films than mineral oil.
- For temperatures less than 70°C, mineral and PAG oils have significantly greater film thickness than PAO oils.
- For temperatures greater than 90°C, PAO and PAG oils have significantly greater film thickness than mineral oils.
It would only be an issue under 70°C. and at those temperatures, the oil is thicker than it needs to be anyway. Remember that the bearings are running hotter than the bulk oil temperature, so if the bilk oil reaches 50°C, the oil in the bearings will easily go over 70°C already.
I'm not so sure about a very high pressure/viscosity constant in slide bearings. I'd be concerned about bearing fatigue if you run in the EHL regime a lot. for roller cams and rocker bearings it's a good thing.