While I usually have some of the same oil used at the last change for top-offs on those engines that require them, I also have about 3/4 of a case remaining of RK HD30, bought cheaply on a Thanksgiving Day special a couple of years ago for top-off use.
My reasoning is that a straight grade has no VIIs to potentially compound the effects of those already present in the remaining sump oil and that it may provide some useful thickening of what will be oil that's suffered some loss in viscosity in use.
A straight SAE 30 might not be the pick in January, but April through October around here it seems like an ideal top-off oil.
What do you all think?
My reasoning is that a straight grade has no VIIs to potentially compound the effects of those already present in the remaining sump oil and that it may provide some useful thickening of what will be oil that's suffered some loss in viscosity in use.
A straight SAE 30 might not be the pick in January, but April through October around here it seems like an ideal top-off oil.
What do you all think?