• Ian Harfield
    23 May 2024 at 07:05 #69769

    Engine Oil?

    We have our recently acquired 16/80 – 2ltr 6 cylinder, we kicked off our ownership experience and clocked up about 500 miles in the last month.

    Knowing that everything works so far as it should, Time to embark on a service. (to get to know the car)

    Following the process set out in the owners instruction book.

    Big question, what engine oil is everyone now using?

    Appreciate all modern Mineral oils will be far better than what existed in 1934, but which one do we feel is best or most widely used.




    Len Cozzolino
    23 May 2024 at 09:25 #69772

    Hi Ian,

    This is not a straightforward question to answer as much depends on when your engine was rebuilt.  IF you don’t know then the safest bet is to continue with the original Lagonda recommendation. The oils Lagonda originally recommended were Prices Motorine C De Luxe, Wakefield Castrol XXL, Mobil D and Aero Shell.  These are all SAE40 straight oils. They would have contained anti-foaming, anti-oxidants and pour point suppressants but not detergents/dispersants. So a single grade SAE40 non-detergent/dispersant oil is what you should use if you are to stick with Lagonda’s original recommendation.

    IF the engine has recently been rebuilt and thoroughly cleaned internally then you can use modern oil, 20W/40 is preferable but the standard 20/50 is fine.

    The next question is, should you use a Detergent/Dispersant Oil in your 20W40 or 50?   The common advice is “Yes” if the engine has recently been rebuilt and fully cleaned, and under no circumstances if not. However, one of the interesting points to come out of Richard Michell’s excellent book is that the answer is probably “Yes” even if the engine has not been rebuilt/cleaned and particularly if your engine still only has the original simple oil filtration systems. There are two reasons to alter this common misconception:

    1.     Dispersants hold the combustion solids in suspension and prevent them from amalgamating together to form large particles which, when large enough, settle as sludge at the bottom of the sump in an unfiltered engine. When these combustion particles are formed they are microscopic and do little damage to the engine. Once the combine to form larger particles they can start to cause damage and start to build up and block oil-passage ways. Their size when they start to cause damage is still too small for them to settle out under gravity as sludge so they are circulating around the engine causing wear. The job of the dispersant is to stop this amalgamation of the combustion particles and hence reduce damage. Together with the detergent it also discourages the tendency for the particles to adhere to the metal surfaces and accumulate there.

    2.     From the 1960’s it was hard to find non-detergent/dispersant oil. So unless the owner was aware and took the trouble to find non-detergent/dispersant oils it is very likely that your engine has used oil with detergent/dispersant in it for a number of years.

    So unless you can guarantee the engine has never used non-detergent oil you are probably safe to use it.

    I hope this is useful

    D C W Humphreys
    23 May 2024 at 11:05 #69775

    I would also add to Len’s comments that I think having a good oil filtration system is particularly important. I dont know what the 16/80 has, but I had one fitted to my 2 litre nearly 25 years ago (by Wessex Workshops) and it uses a modern spin on filter. If you use a high detergent oil (as I do) and dont have any system to remove the particulates generated, then you might need to seek further advice.

    What is the best oil to use is a famous question on most forums….. I guess the main thing is to ensure it has high levels of ZDDP (>800ppm) which most oils for modern cars dont have as it can affect the catalytic converter. I have used Bicester Classic Oils 20/50 for sometime, but am currently using Millers Classic Sport 20/50 (and as Len mentions there are plenty of others).

    I think that the old adage “it doesnt matter what quality oil you use as long as its changed frequently” may have applied 20 years ago, but doesnt now since classic oils hove improved a lot so I think worth using a good quality/known brand.

    If you dont know what’s in your vehicle, you could get it tested then just stick with that… I think that Bicester Classic Oils, Millers, Castrol etc all offer this service. You might find the results interesting anyway as it could give an indication as to the health of the engine.


    Ian Harfield
    23 May 2024 at 15:17 #69784

    Len, thank you, and for the information you shared directly

    Ian Harfield
    23 May 2024 at 15:20 #69785

    Getting the existing oil testing will be a roller-coaster of emotions waiting for the results! but as you say it will give a clear indication of the health of the engine, and fingers cross no evidence of metal particals.

    Thanks for the advice.


    Richard Branch
    8 June 2024 at 19:48 #69900

    A couple of great posts there, thanks chaps…

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