Volvo Owners Club Forum - View Single Post

AndyV7o · Jul 12th, 2018, 10:47

No, engines are engineered well and a 10w40 would have no benefits. Its partly the reason that modern engines can greatly outlast old engines designed around the thicker oils of tge day.
0w is the better grade when cold, the hot value of 20/30/40/50 etc doesnt have a lot of bearing on how tge oil is behaving in the critical areas, this is where the HTHS value represents the better picture of how an oil is behaving in terms of flow, oil cushion, etc. The spec of the oil stipulates the hths and lots of 30 and 40 oils for example have same/similar hths values which means they flow and form oil 'cushion' (the hydrodynamic body of oil which the spinning journals effectively float within inside the bearing) etc just the same. Thus is why manufactures tend to use a spec rather than a viscosity these days, they still have a viscosity range as it does matter, but not as much as hths. Afaik ALL the oil specs of manufacturers and acea have a stipulated hths value, whereas a lot of specs are available in multiple viscosities.
So, yeah, a manufacturer may spec B5 and have designed the engine around it, but it could still wear faster than if a B4 was used. Similar with c specs, C3 for example is effectively a mid saps version of B4 and should in principle be backwards compatible, but, it still over (a very) long term performs slightly poorer, and the saps substitutes only work well in the right environment, some engines would/will wear excessively if C3 is used in place of B4.
If however you were to try and use a 0w30 B4 in place of the new volvo spec designed around C5 (ro20 thingy-bob 0w20) you'd give the thing problems, starving areas of oil as even though the grade is not too different the hths is massively different.

There isnt an ideal oil unfortunately, it depends on craploads of things, A3/B4 is close to udeal, but not in certain engines and is bad for dpf's, which then shifts in favour of C3 which isnt quite man-enough in terms of anti-wear ingredients for certain engines.........
The fuel savings are minimal, the environmental improvements of C specs is worthwhile.
Design an engine to work optimally with C4 and you are close to nirvana....

Jul 12th, 2018, 10:47	#21
AndyV7o Premier Member Last Online: Jun 21st, 2021 20:47 Join Date: Jun 2018 Location: Creswell	No, engines are engineered well and a 10w40 would have no benefits. Its partly the reason that modern engines can greatly outlast old engines designed around the thicker oils of tge day. 0w is the better grade when cold, the hot value of 20/30/40/50 etc doesnt have a lot of bearing on how tge oil is behaving in the critical areas, this is where the HTHS value represents the better picture of how an oil is behaving in terms of flow, oil cushion, etc. The spec of the oil stipulates the hths and lots of 30 and 40 oils for example have same/similar hths values which means they flow and form oil 'cushion' (the hydrodynamic body of oil which the spinning journals effectively float within inside the bearing) etc just the same. Thus is why manufactures tend to use a spec rather than a viscosity these days, they still have a viscosity range as it does matter, but not as much as hths. Afaik ALL the oil specs of manufacturers and acea have a stipulated hths value, whereas a lot of specs are available in multiple viscosities. So, yeah, a manufacturer may spec B5 and have designed the engine around it, but it could still wear faster than if a B4 was used. Similar with c specs, C3 for example is effectively a mid saps version of B4 and should in principle be backwards compatible, but, it still over (a very) long term performs slightly poorer, and the saps substitutes only work well in the right environment, some engines would/will wear excessively if C3 is used in place of B4. If however you were to try and use a 0w30 B4 in place of the new volvo spec designed around C5 (ro20 thingy-bob 0w20) you'd give the thing problems, starving areas of oil as even though the grade is not too different the hths is massively different. There isnt an ideal oil unfortunately, it depends on craploads of things, A3/B4 is close to udeal, but not in certain engines and is bad for dpf's, which then shifts in favour of C3 which isnt quite man-enough in terms of anti-wear ingredients for certain engines......... The fuel savings are minimal, the environmental improvements of C specs is worthwhile. Design an engine to work optimally with C4 and you are close to nirvana....