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oil for straight


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First question for you to ask is what type, and brand of oil has been used in the engine? Swiching brands is a no no.


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The short answer is "nothing special". All of our modern oils are superior to the engine oils of 1950.

If your engine has been stripped and rebuilt,and is therefore internally clean, then use a modern 20/50 oil. At 59,000 miles I suspect it has not. This means that there will be some build up of dirt in the engine from the old oil and fuel. Modern high detergent oils hold the dirt in suspension to carry them to the full-flow oil filter. Old non-detergent oils allow the dirt to sink to the bottom of the large sump pan. Consequently, you should go for a low detergent, probably mono-grade oil, to avoid dislodging old deposits. I use a monograde. low detergent, SAE 30 "classic" oil, which is inexpensive and can be changed often. You can use it in lawnmowers too !!

The brand is not important, provided it is of reasonable quality. You will not be looking for extended drain intervals will you?

There is no point spending money on full synthetic oils for our cars, as these are generally of too low a viscosity and only viable if you use extended drain intervals. It is better to use a cheaper oil and drain it often because of the signifcant piston blow-by and poor oil control of our older engines.

Some people over here use Castrol R, castor based racing oil for vintage racing. This makes a nice smell, but cannot be mixed with mineral oils. There should be no problem mixing standard mineral oils with each other, or with synthetic.

Hope this helps.


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If you have hydraulic lifters the 20w-50 might be to heavy and the lifters might become very noisy!

I've just been through this hair pulling situation.

If you experience noises go for a 10w - 20w monograde (as per specs in your shop manual)

or a 10w-30.

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