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  • #6826
    david Moseley

    Andy raises a good question as to what engine oil is best for ours cars Are pure synthetic Oils  a no no for our cars. Should you use a  pure mineral Oil or a mixture of synthetic and mineral and should you use an additive. I have never added ZDDP to the oil I put in the engine. Both my cars have 6Cyl overhead valve engines and I use Millers 20/50 Pistoneeze or Morris 20/50 golden film. Both contain ZDDP though I don’t know how much. Its usually about 0.01%. Morris also have a 15/50 which has a “HIGH ZDDP” on the label. It is classed as a racing oil. What is the difference ? The other oil is Driven which have an oil good for older engines which are not in regular use. It  has a “high Zinc content”. This oil is much more expensive so it must be better or is it ?. They all contain detergents so presumably are not pure mineral oils  I have put modern spin on Oil Filters on both engines which are more efficient,  easy to change and cheap to buy.  If you don’t have an oil filter you should not have an oil containing detergents or is that incorrect. I would be interested to hear members views and what oil they use. Do you like Andy P add ZDDP and if so how much.  Maybe an article in the magazine from someone who knows much more than I do David


    I use a multi grade 20/50 in my P1 as it has fully floating big end shells and doesn’t have great oil pressure. The K1 on the other hand has 8 ba conrods  and tagged big end shells, which gives me 50 psi oil pressure, normal running, 20 psi on tickover  when hot,  using multi grade 15/40 oil. This is oil with detergent added, but my K1 has a full flow spin on  oil filter and I usually change the engine oil every 1000 to 2000 miles. My P1 has covered at least 60000 miles since I put it on the road back in 1996, and has just needed on exhaust valve replacing. Still going well.

    Tim Wilson
    • Very interesting and thought-provoking points, David – thanks for this. I always threw Duckams 20/50 into my old bangers, right back from when l got an Austin 7, 54 yrs ago. Nowadays, in the Allard, Land Rover and TR3 l always use Halfords 20/50 which, so far as l know, retains sufficient ZDDP in its composition. The 21-stud in the Special has no oil filter, so l just change the oil once a year, by which time the car won’t have done more than 3k miles (much, much less, this last year!). But l suppose these engines are old and unsophisticated in design, and are likely happy on relatively simple (and cheap!) lubricants. Looking forward to hearing what more experienced Allardistes than l, have to offer on this. Tim.

    • The 21ZDDP


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