Thread: Oil question
View Single Post
Old 02-23-2019, 03:43 PM   #50
Civilitas
Senior Member
 
Civilitas's Avatar
 
City: PNW/Seattle-ish
Vessel Name: M/V Peter Iredale ;)
Vessel Model: rusting hulk
Join Date: Feb 2018
Posts: 128
Quote:
Abundant natural gas may mean more synthetic content in lube oil due to market pressures. Backward from what might have been expected in recently past years. Good enough is probably better than ever.

This has been and is happening. The term "conventional oil" is about to disappear. In one amusing case, a few years ago the API (Amer. Petroleum Institute) was doing a periodic sampling and testing of virgin (from the bottle/unused) 5w-30 conventional oils. The Pennzoil product was simply off the charts and clearly not conventional. The samples had been purchased at retail facilities, not manufacturer provided. This was also noted in used oil samples being reported on automotive forums. The reason was the excess capacity from Shell's "Pearl" GTL natural gas facility in Saudi Arabia. Shell was simply sticking the gas-to-lube synthetic into their plain 'ole yellow bottles as it was more economical.

On the subject of viscosity and temperature, here is the graph I mentioned above. Bacchus pm'd me suggesting Drop Box, though I can't find a way to insert it, only link it.

https://www.dropbox.com/preview/Visc...?role=personal

Note first the x-axis is linear and in degress Celsius. The y-axis is in cSt (viscosity) but logarithmic.

This is a representative comparison of a 0w-30 vs 10w-30 conventional S(park) rated oil. C(x) diesel oils will be the same, apples-to-apples. Note that even with a 0w rating, there isn't much difference at all in pumpability until -10C (15F). You really have to get below 0F for real-world differences to manifest.

One might be tempted to say "OK, but so what? Why not take the added protection?" The reason not to, if it's not strictly needed, is the adulteration of the lube by additives that wear out more rapidly and do not lubricate/protect. The raw percentage of these in conventional oil can be as high as 20%, I have read, in 0w and 5w oils trying to meet a 30 grade rating when hot.
Attached Thumbnails
ViscosityGradesGraph.jpg  
Civilitas is offline   Reply With Quote