Originally Posted By: Benito
Apologies for breaking up your post but I need to in order to ask the following:
I understand why 3 follows 1.
But are you saying in statement 2 that the AW additives are in thin and thick oils in similar amounts but that the thin oils utilize them more?
no problems, if it helps understanding.
Looking at the Stribeck curve, the bottom axis is (speed x viscosity)/load, the side axis is friction.
Areas to the right of the minimum point are in full hydrodynamic, parts separated by an oil "wedge", and are in theory no contact/no wear.
The bit to the left of the minimum is where contact has been made, and boundary/mixed lubrication takes hold...the friction in a plain oil rises markedly...friction modifiers can be added, that react with the surfaces that are just touching, and makes a soft, soapy, sacrificial layer...the friction is lower than hydrodynamics, but some metal loss exists (but nothing like what would happen with no FMs).
An engine will have different components running in different regimes. bearings should be hydrodynamic, cams are quite mixed lubrication, and pistons and rings are full hydrodynamic mid stroke, and boundary at either end.
So changing to a thicker viscosity moves the curves to the right, lower viscosity to the left.
The latter point is why I say that the additives are more utilised in a thinner oil, everything moves farther left.
It's part of the warm-up wear problem, in that cold thick oil is thinning with heat, and the additives aren't that effective on relatively cold surfaces.
In addition, Xw30 and lower viscosity engine oils, under the ILSAC banner, have lower traditional (ZN, and P) additive treat rates (to limit aftertreatment damage with implied higher consumption), and the EC oils typically have organic FMs and the like which help take their place.
So getting back they have mostly similar additives, but the thinner oils have less of them, and with a couple of others added.
That's why I'd recommend a properly formulated 10W40, over taking an ILSAC 5W30 and trying to make it a 40 with Lucas. The 10W40 will have typically higher additive rates than the 5W30 to start with, and THEY will be further diluted by the Lucas.
You end up with something that has nothing beneficial over the 10W40, and the possibility of losing on every front wear wise, durability wise, oxidation resistance wise, and TBN wise.
turtlevettes misquote (directly aimed at, and misquoting my argument) either demonstrates that he's just baiting and misinforming for sport, or really is missing the big picture.
Apologies for breaking up your post but I need to in order to ask the following:
I understand why 3 follows 1.
But are you saying in statement 2 that the AW additives are in thin and thick oils in similar amounts but that the thin oils utilize them more?
no problems, if it helps understanding.
Looking at the Stribeck curve, the bottom axis is (speed x viscosity)/load, the side axis is friction.
Areas to the right of the minimum point are in full hydrodynamic, parts separated by an oil "wedge", and are in theory no contact/no wear.
The bit to the left of the minimum is where contact has been made, and boundary/mixed lubrication takes hold...the friction in a plain oil rises markedly...friction modifiers can be added, that react with the surfaces that are just touching, and makes a soft, soapy, sacrificial layer...the friction is lower than hydrodynamics, but some metal loss exists (but nothing like what would happen with no FMs).
An engine will have different components running in different regimes. bearings should be hydrodynamic, cams are quite mixed lubrication, and pistons and rings are full hydrodynamic mid stroke, and boundary at either end.
So changing to a thicker viscosity moves the curves to the right, lower viscosity to the left.
The latter point is why I say that the additives are more utilised in a thinner oil, everything moves farther left.
It's part of the warm-up wear problem, in that cold thick oil is thinning with heat, and the additives aren't that effective on relatively cold surfaces.
In addition, Xw30 and lower viscosity engine oils, under the ILSAC banner, have lower traditional (ZN, and P) additive treat rates (to limit aftertreatment damage with implied higher consumption), and the EC oils typically have organic FMs and the like which help take their place.
So getting back they have mostly similar additives, but the thinner oils have less of them, and with a couple of others added.
That's why I'd recommend a properly formulated 10W40, over taking an ILSAC 5W30 and trying to make it a 40 with Lucas. The 10W40 will have typically higher additive rates than the 5W30 to start with, and THEY will be further diluted by the Lucas.
You end up with something that has nothing beneficial over the 10W40, and the possibility of losing on every front wear wise, durability wise, oxidation resistance wise, and TBN wise.
turtlevettes misquote (directly aimed at, and misquoting my argument) either demonstrates that he's just baiting and misinforming for sport, or really is missing the big picture.
