I have been faithfully using HD30 so far because 'the A-4 was designed for it and that is what the manufacturer recommended.' However, I am having second thoughts.
Mainly because in the last issue of Good Old Boat, there is a nice article by Robert Hess about the A-4. Among other observations, he notes that the manufacturer actually changed the specifications, recommending HD-30 for hot weather and 10-W30 for year-round use.
This makes a lot of sense. There is a reason why nearly all modern cars run on multi-weight oil: you want low viscosity (10) when the motor is cold and high viscosity (30) when it is hot. Why should it be different for an Atomic 4?
Of course, early on Universal could not recommend multi-viscosity oil simply because it did not exist, but once it was well established (70s or 80s), that's what they apparently recommended.
I know that Don says one can use 10W30 'in a pinch' which does not make it sound that he recommends it whole-heartedly. I would be very interested in getting the straight dough here. Are there any advantages of using single weight 30 oil over 10W30?
[I will be putting in an oil filter soon and in the process will 'flush' the whole system with new oil several times. It would be great to know which oil will be the best to use. Also, I buy 10W30 for my vehicles by the case while the A-4 is the only motor I have that uses HD30. Using 10W30 would make this part also a bit easier although this is a very minor concern]
--Ernst
Mainly because in the last issue of Good Old Boat, there is a nice article by Robert Hess about the A-4. Among other observations, he notes that the manufacturer actually changed the specifications, recommending HD-30 for hot weather and 10-W30 for year-round use.
This makes a lot of sense. There is a reason why nearly all modern cars run on multi-weight oil: you want low viscosity (10) when the motor is cold and high viscosity (30) when it is hot. Why should it be different for an Atomic 4?
Of course, early on Universal could not recommend multi-viscosity oil simply because it did not exist, but once it was well established (70s or 80s), that's what they apparently recommended.
I know that Don says one can use 10W30 'in a pinch' which does not make it sound that he recommends it whole-heartedly. I would be very interested in getting the straight dough here. Are there any advantages of using single weight 30 oil over 10W30?
[I will be putting in an oil filter soon and in the process will 'flush' the whole system with new oil several times. It would be great to know which oil will be the best to use. Also, I buy 10W30 for my vehicles by the case while the A-4 is the only motor I have that uses HD30. Using 10W30 would make this part also a bit easier although this is a very minor concern]
--Ernst
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