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Engine oil choice

Posted: Wed Mar 06, 2019 5:40 pm
by p2roverman
I've been advised there are two types of so-called 'classic' oils, that with detergant, and that without. Note that not all companies may offer this choice, but Millers Oils do.
The theory is that their 'classic' oil has detergant which keeps contaminents in suspension until the oil goes through a micro-filter, as found on a P3 and all later models. (Oil in a P3 and early P4 wil take longer to be fully cleaned due to the filter being only a bypass type). All standard modern oil has detergant, especially that specified for diesels.
Their 'vintage' oil has NO detergant, so that contaminents will drop out of the oil and settle in odd corners, eventually buiding up into a thick layer of sludge in the sump bottom, but importantly, not being continuously re-circulated through the engine causing damage and wear.
Something to think about when next buying oil for an engine like a P2 which only has a basic mesh filtration. Duckhams 20/50 perhaps not being the best universal solution!

Re: Engine oil choice

Posted: Fri Mar 15, 2019 8:22 pm
by Geoffrey
Hi,

Choice of oil for old vehicles seems to be a never ending source of differing opinions. I have several classic motorcycles as well as my Rover 12. None of these vehicles have what you could call an oil filtration system. I have decided to try and take advantage of the benefits of a modern oil. I have a Sunbeam S8 motorcycle that has an oil in the sump engine like a car. Recommended for the bike is straight 50 engine oil. I have realised that when it gets really hot it thins out to the consistency of water but when cold was quite thick and heavy. So probably lacking in good lube qualities when hot and takes too long to get to the bearings when cold. Millers do a Classic Sport 20/50 engine oil in semi/synthetic or fully synthetic form. It is mildly detergent I believe. This oil is much better at maintaining viscosity than the old oils and is thin enough to get to bearings quickly. I think as long as the oil is changed regularly then it will not get too dirty and the amount of contaminants in it will be at a fairly low level. Millers brand this oil Pistoneeze and they recommend it for classic post war vehicles. Indeed the fully synthetic version is aimed at classic cars used for racing. This is what I have put in my Rover as well as the Sunbeam.

Geoff

Re: Engine oil choice

Posted: Tue Jun 25, 2019 6:57 am
by kevh
The Millers vintage oil is available as 30, 40 and 50 sae, forgive my ignorance but why and which one to use?

Re: Engine oil choice

Posted: Tue Jun 25, 2019 7:27 am
by Geoffrey
The old idea was that you used a thinner grade in the winter and thicker in the summer. I personally would not use these old single grade oils. Oil technology has moved a long way since the 1940s. Whilst many modern multigrades are really only suitable for modern engines with very fine tolerances, there are 20/50 multigrades on the market which are formulated as suitable for old engines with minimal filtration systems. The Miller pistoneeze product mentioned is one of these.

In the 1970s I worked for Duckhams Oils as a computer programmer. I helped write programs to analyse the results from oil testing developmental equipment. There was absolutely no doubt in the oil technology engineers minds that multi grade oils offered very significant benefits over the old single grade oils for all types of four stroke engine. Duckhams 20/50 was in its day 'a great leap forward' in oil technology. Of course it does not feature in the oil recommendations made by manufacturers from earlier times because it wasn't invented then!

Oil manufacturers still market single grade oils as 'being suitable for older engines'. Well, yes, but, what they are not claiming is that they are the best for older engines. They are simply fulfilling a demand from people who think they should put 1940s oil in their 1940s car.

Re: Engine oil choice

Posted: Tue Jun 25, 2019 9:18 am
by kevh
Thanks Geoff,

So, head on the block, using your industry knowledge, in 2019 which oil should I put in my 1935 12?

Or, considering the very low mileage most vehicles of this age will be doing is it at all important and do we have unnecessary concerns about using the "correct" products?

Re: Engine oil choice

Posted: Wed Jun 26, 2019 7:09 am
by Geoffrey
I am not an oil technologist but did work with them. I would put a 20/50 formulated for a classic car in your Rover 12. Halfords do a straightforward mineral one. I put Millers semi-synthetic Pistoneeze in my 1947 12.

It is expensive but I see no point in scrimping on oil, because I use mine regularly ie at least twice a week. I suppose if yours only goes out on high days and holidays might as well put Halfords in it. A multi grade will get to your shell bearings quicker than thick straight 50 or 40 when the engine is cold. It will also hold its viscosity better when the engine is hot.