Sunday, 9 September 2012

Oils for older petrol engines (revisited)

I had discussions with two classic car drivers yesterday, one was Colin with his 1952 Bradford Utility which became his Jowett Special, its a good read as the book he wrote and published named Myra (some copies may still be available)

Colin Davies with a copy of his book named Myra, he is standing next to our 1967 Singer Chamois.

This car is now some sixty (60) years old, its supercharged and was a succesfull entrant in the Lands End Trials in England, Colin tells me that as far as he knows, only one other Jowett exists in South Africa? The front suspensions are of interest to my self, the uprights and the steering rack are pure Hillman Imp!

The other asking for information was Terence and up in Johannesburg, he has just fitted some new piston rings I supplied him for his race Imp. The engine is in his  Imp and was suffering from smoke, thought to be caused by faulty piston rings? I mentioned to Colin and Terence that the oils we are offered today are very different to those sold when our cars engines were designed. (he has been using Shells 40 grade diesel oil, I have no idea if this is a good idea or not?)

Dudley Dix in the USA found an item on the Lotus Europa Forum about this subject, its based on the fact that older oils had more solids in them than modern oils.

Interesting and controversial stuff. There was a lengthy discussion about oils and additives on the Europa Forum a few weeks ago. From that I understand that oils of a few decades ago contained much more zinc, boron and sulphur and that those minerals were needed by the engines of the time. Modern engines are made from much harder alloys and they don't need as much of those minerals, so modern oils have much less in the interests of lower emissions. That leaves the classic cars out in the cold, with modern oils inadequate for their engine needs. This applies particularly to motors with flat tappets, which wear badly without enough sulphur. They need either additives or oils that contain more of those minerals than standard. I will research the database before I fill up my motor after rebuild but I think that the outcome was that there are some racing oils that do have what is needed but most of the off-the-shelf oils don't.


You will find this information in the link below,its very good reading!

I use both of these makes and to good effect, the Singer uses no oil at all with the Shell HX5, its the same with the 1966 Jaguar 3.8S type and with Castrol GTX for older engines, no noticable oil use at all.


PS, you need to read this blog to get a better idea on the subject.

Note, the oil I mentioned as being our normal Imp 998cc race engine choice was Duckhams Q20, that was a 20-50 grade and the race Imp ran very well on that oil, do Castrol now own Duckhams?

This blog covers Shells new offering and is not the oil I am using in my older car engines.