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Oil and ZDDP

Technical issues not related to a DLOC car marque, eg tyres, ethanol, other car makes, etc. and legal, political and insurance
JT7196
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Re: Oil and ZDDP

Post by JT7196 »

Hi Chris, interesting about the theory of increased oil leakage using Synthetic Oils, and their effect on seals.
Most of the early Lanchester engines used the Scroll type of seal, so perhaps it may be true that the thinner grades may leak more, only by experimenting will I eventually find out I suppose !
It is seemingly evident that my engine would benefit by using one of the multi grade oils, so I will see what's available locally, and make what I hope, is an "Informed" choice.

Cheers A'l :D :D :D

Chris_R
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Re: Oil and ZDDP

Post by Chris_R »

Big A'l wrote: Thu Jun 08, 2017 5:09 pm Hi Chris, interesting about the theory of increased oil leakage using Synthetic Oils, and their effect on seals.
Most of the early Lanchester engines used the Scroll type of seal, so perhaps it may be true that the thinner grades may leak more, only by experimenting will I eventually find out I suppose !
It is seemingly evident that my engine would benefit by using one of the multi grade oils, so I will see what's available locally, and make what I hope, is an "Informed" choice.

Cheers A'l :D :D :D
Except they're not thinner. A 5W-40 is not thinner than a straight SAE40 or a straight SAE30. Even a 0W-40 would not be thinner.

Phillmore
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Re: Oil and ZDDP

Post by Phillmore »

With all my classics I have always turned the engine over from cold without the choke until the pressure gauge registers good pressure (if it has a gauge) then pull the choke out to allow it to fire up.

I think I understand the very informative data and logic you're providing on oils Chris and it's obviously not a simple subject with many variables, and as you say, original specifications were only as good as the available oils of the day BUT . . . . If I read you correctly we should probably all be using semi-synthetic or synthetic oils in our old cars these days?
Andy

1954 Conquest Mk1, 1956 Conquest Mk2, 1957 Conquest Century Mk2, 1955 Austin A90 Westminster

Chris_R
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Re: Oil and ZDDP

Post by Chris_R »

From all the research that I have done into oils and oil technology and how it works in the engines, that is my belief Andy.
It's what I use in my Jensen (my Daimler is not running but when it does I will use the same) and have done for the last 5 years and 20,000 miles (so far). But not blindly. I am quite happy with the way it performs and it wasn't until after I'd done it myself in my own car and racked up a good ten thousand miles that I published the original article that was in DM. I felt I had to put my money where my mouth was first so to speak.
Others may believe differently and there are engine builders that swear by "good old" 20W-50 mineral oil, diesel oil and all sorts. I've had this discussion in other forums and despite presenting the facts, there are those that believe Joe Bloggs, engine builder, knows more than the original manufacturer!
If you are comfortable and prefer to stick with the traditional mineral 20W-50, don't get me wrong, if you've been using it then it's been working for you for many years and it will continue to work for you if you continue to use it. It's just that I believe you can do better and provide better protection with the more modern products and this whole topic attempts to explain why and to dispel some of the myths and half-truths that are told as facts.

JT7196
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Re: Oil and ZDDP

Post by JT7196 »

Hi Chris, so are "We" right in assuming, that you use fully Synthetic oil in you car ?
Cheers A'l :D :lol:

timmartin
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Location: Berkshire

Re: Oil and ZDDP

Post by timmartin »

Thank you Chris...and further to Al's question, how would you decide whether you were worried about forming "sticky deposits, particularly in the piston rings" when using fully synthetic?
(As a result of the amount of water from combustion that gets into the oil of our old engines, and may not be boiled off)
Tim
Blue 1964 SP250 in Berkshire

Chris_R
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Re: Oil and ZDDP

Post by Chris_R »

That depends on the amount of use and the length of your journeys. If you regularly only use the car for very short journeys you are going to have an issue with condensation because it never really gets thoroughly warmed up and there isn't time for any condensation or lighter contaminents to boil off. Only you know how you use your car and can decide what is best from the vast choice that is available. My personal choice on a mineral oil would be a Mobil 15W-40, Shell Helix HX5, Castrol GTX or something like that. If I were to choose on the synthetic line, I would choose either a 10W-40 or 5W-40 from the same group, possibly also Petronas although I don't know much about that company.

Dobbinridesagain
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Re: Oil and ZDDP

Post by Dobbinridesagain »

Belatedly chipping in here... of late, I have been using Lucas Classic 20/50, having abandoned Comma Classic when they reduced the zddp.

In another car, I am using Lucas Hotrod 10/30 because of the zddp level and in the belief that I should stick to the original viscosity requirement for my 1963 car because it has hydraulic tappets and a viscosity change will affect their operation.
Am I wrong?

I am also motivated to ask this question because the Lucas oil costs £39 a gallon, and although the cost is piffling compared to an engine rebuild, my inner Scrooge cringes.

Ivor

PS, at the moment, neither of my cars is a Daimler, but of course forum members often own other cars.

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