Guy Lachlan from Classic Oils visited the Hagerty stand at the 2017 Silverstone Classic where he was interviewed by Georgina Yeomans. Guy explained why classic vehicles have very specific lubrication requirements, and why using the right oil is essential in maintaining a healthy engine.
How much is your car to insure? Find out in four easy steps.
Get a quote
I could not agree more with Guy Lachlan about using the right oil is essential. However, experience shows us that Penrite is not the right oil if you have a car using cross shaft gears. Penrite has proved a disaster in vintage twin Camshaft Salmson engines.The recommended Penrite has insufficient film strength to safeguard your engine. Experience shows that one can expect cross shaft failure after only 20 miles. Castor oils are the only safe oils to use in these engines.
I run a 1972 Porsche 911 2.4 with Manual Fuel Injection. The original specified oil is SAE30 but I have used the Halfords Classic 20W50 since 2005. Its green so there may be a clue there. My local Porsche engineer would use Castrol Magnatec if I let him do my oil changes. Is there something better on the market that I should be using?
Hmm, I assume your Porsche is an air-cooled version as the manual specifies straight 30. As there is no accurate way of controlling engine temperature in an air-cooled engine, then I’m told that multigrade oil e.g. 20/50 might break down due to overtemperature destruction. Water cooled engines generally sit at around 90 degrees.
Regarding the comment about Salmson cross-shaft gears I should observe that before a cold start it is important or essential to put some oil in down the filler. Some of this reaches the cross shaft. Secondly, the steel, steel, steel gear combination is a disaster and in the 1970s I got some sets made with a phosphor bronze intermediate (ie cross shaft gear) so the contact was steel, bronze, steel. I think this worked well – at least mine were very durable, Failing that I can see that castor is good because it is likely to still be stuck on to the gears during start up and does not drain off like multigrades and even single weight 30s (which in my view are far too thin anyway).
Hello everyone, I’m the ‘guy’ in the video, and with some trepidation I thought I’d address the points raised so far. The Salmson cross-shaft is indeed an interesting and challenging gear set to lubricate, and as you say film strength is everything. Castor is certainly a good option, but has drawbacks including cold starting (monograde) and degradation over time. Nowadays there are Full Ester (PAO) synthetic engine oils which also offer enhanced film strength and act on the wearing faces in a similar way to Castor oils thanks to electrostatic forces, but have the benefit of being multigrade (and are also tolerant of methanol). Penrite and others make suitable viscosities in their Racing range for vintage cars, and we have several customers racing cars using these oils. Not trivial to switch over from Castor though, I realise! Regarding the ’72 911 the green colour of the Halfords / Comma oil is simply colouring, presumably added to make one think of Duckhams – it is not however the same spec as Duckhams was. You can use a high-Zinc Group 3 Synthetic in that engine with good results. The Penrite HPR15 (15W60) is a good example, but there are others. The 60 number protects the engine in the event that it runs hotter than normal, which as others have said is more likely in a air-cooled application. Hope this helps, but do call us on 01869-227062 if you’d like to discuss any of this in more detail!