Classic Car Parts

Classic car motor oils

The question on what kinds of oils to use for our classic cars, is coming up from time to time.
In general check your instruction manual for recommended oils. Please note – this is not a research article, just my personal experience on what oils that work for my engines; there are many alternatives, and comments/input is appreciated.

I have two cars, on which I’ve tested out a few alternatives, based on suggested oils from forums and producers.Triumph TR6 PI Man/O and a Jaguar MK2 1962 M/O 3.8L

The oils I currently use

Engine
Castrol Classic 20w50

Gear box (manual w/overdrive)
Comma gear oil GL-4 (http://www.commaoil.com/productsguide/view/6/183 )

Rear axle/dif.
Penrite 80w90 hypoid oil GL-5
(http://www.penriteoil.com.au/products/manual-gear-&-differential-oils/hypoid_80w-90)

Why this engine oil

In general the engine viscosity (fluidity/thickness) I’m after, for my 60’s and 70’s classic cars, is something like 20w50. The number 20w tells you how easy it will be to start the engine in cold weather; the number 50 is the thickness in warm weather, or when the engine is warm. 20w50 is fairly thick oil.

There are many good alternatives (offered by e.g. Penrite, Castrol, Redline). I have good experience with Castrol classic 20w50 oil, and chose this because:

It has high levels of Zinc, which can affect your classic engine in regards to high pressure friction, and the combination with e.g. Phosphorous is good.
It is fairly cheap and accessible where I live ( - not entirely true, in Norway a can of 4,5 liters is almost €100 in my local shop, but only €23 when ordering from abroad + freight – so order online . e.g. from Moss or SCParts).
Saying this, I am going to try out Penrite products later this year.

Why this gear box oil

Previously I was not really that interested in what gear oil to use, a gear oil is a gear oil. The Triumph had to cope with Biltema gear oil GL-5 spec, and even an auto. box gear oil for some time. However, GL-5 spec oil is not good for yellow metal; it will be damaged by GL-5 oils over time, so now all dried and filled up with Comma’s GL-4. The gear box sounds happy also. I don’t think I would have chosen Commas 20w50 engine oil, as they have (to my knowledge - not confirmed) low values on the Zinc content, but the gear oil seems fine (and locally accessible in Bilextra and quite cheap).
I first bought the Penrite 80w90, but this turned out to be GL-5, so I dropped it.

Why this hypoid oil

The Penrite alternative seems to be working quite good for me (and the Jag+Triumph), it is accessible and sensibly priced. The only drawback is GL-5 spec, which isn’t what is correct for these cars. However, I’m not so worried about the yellow metal factor here, so I’m sticking to this oil until experience (mine or others) tells me otherwise. Rear axels with GL-4 specified does not (no guarantees from my side) have yellow metal components, so GL-5 should work perfectly fine.

Easy the order online from abroad (here in Norway everything is expensive) from Sngbarrat etc.

Recommendations from oil brands

I have contacted several oil brands to get their recommendations regarding oils for classic cars, and also got some feedback about additives and e.g. zddp levels.
Positive and informative response is received from a few of the oil brands. Below you can see their replies – I recommend reading it all the way through.
I only quote companies that have given me permission to quote them.
Note that any recommendations are not definitive.

To summarize

Not recommendet to use additives to the engine oils at all.
The classic car mineral oils contain enough Zinc etc. for our cars.
Use a running-in oil/break in oil after a rebuild
If engine rebuilt to modern standards, no reason not to use synthetic oils.

Castrol

October 15th, 2012
Andy Griffin, Lubricants - Advanced Technical Support at Automotive Lubricants - UK & Ireland
October 23rd, 2012
Similar information was newly provided by Castrol/BP in Norway, via Roy Bekkestad.

What running-in (break-in) oil do you recommend for this kind of classic cars?

“I would suggest a basic mineral oil such as Castrol Classic XL30, this would allow better bedding in or the new components”

What engine oil do you recommend?

“Depends on the car, the engine, the use etc ... You could run the period oils, Classic XL30 or XXL40. If the engine is in good condition and does not burn oil then I see no issues using a GTX15W-40 or 10W-40 or even Magnatec 10W-40 as this will offer better starting, faster circulation - but will offer the same "working temperature" performance as the monograde of the same viscosity. The only issue is that modern oils are good at cleaning away deposits so if these deposits are helping to seal an engine, once they are gone, the problem is uncovered, and the oil will be blamed although the oil has just revealed a problem that was always there anyway. If the engine has been rebuilt to modern standards, once run in there is no reason why you couldn't use a full synthetic oil if you so wished for maximum performance and protection - EDGE 5W-40, or even EDGE 10W-60 would be worth investigating. However, every car has it's specific needs based on the comments above regarding use, age, condition so its sometimes best to look at each car rather than generalise.”

Do you recommend additives (in that case what/how much)

“I would NEVER condone adding any aftermarket additives to an oil as these may seriously affect the performance and would certainly affect the specification of the oil.”

The recommended engine oil - what level of ZDDP (if any) and relevant additives does it have?

“Castrol oils generally contain around 900 - 1100PPM of zinc, but it's not just the zinc that is important, the Phos levels are also important - we think that the levels in our oils are perfectly adequate for these engines, the oils these days have stronger fluid strengths so better at resisting fluid breakdown.

There are many people who think that the more zinc the better, this is not always the case as too much can be worse than not enough as this can lead to pitting of engine components

In the USA there has been some reduction in the zinc levels in some high performance modern oils to around 700ppm, then these would not be desirable, however, these would not be used in older engines anyway as they tend to be thin full synthetics ( ie 5W-20 grades ) There is much noise around modern oils and older cars on American websites.

There are many people who have their own ideas as to what is best and no matter what you say they will ignore your help, but I would be quite happy running a TR6 or old Jaguar on GTX 15W-40 or Magnatec 10W-40 if the engine was in good condition. If the engine is worn, or using oil, then the more viscous Classic XL 20W-50 would be maybe more suitable.”

Other related sources of information:

For Castrol’s classic oils, follow this link: http://www.castrol.com/castrol/sectiongenericarticle.do?categoryId=9014107&contentId=7027099
For specs about the Castrol XL 20w50, click here: http://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/B2813B703B57F3CD802577ED004809AC/$File/BPXE-85KMZS_0.pdf

Penrite

October 15th, 2012
Alan Jeffery, Melbourne Technical Department, Penrite and Martin Gough, General Manager, Penrite Oil Company UK and Forest Lubricants UK Ltd

What running-in (break-in) oil do you recommend for this kind of classic cars?

“We recommend our Running-In Oil for the first 500km following an engine rebuild. This is mineral, high in zinc and not friction modified. Its low specifications help to produce the small amount of engine wear that is necessary to ensure that the piston rings are fully bedded-in. (..).”

What engine oil do you recommend?

“We regard a level of zinc at 1000ppm or higher to be "full zinc" and our Classic range of oils contain 1600ppm to keep the classic engines really happy. If the car is driven more-or-less weekly (or more often) then the equivalent HPR oil may be used instead. (Classic Light/Medium/Heavy equate to HPR30/40/50 in turn). In the European market we have Classic 20W-50 available."

Do you recommend additives (in that case what/how much)?

“Additives are easy. We make our oil ready to use, so do not recommend any further additives: they would change the formulation of the oil in ways that are hard to predict.”

The recommended engine oil - what level of ZDDP (if any) and relevant additives does it have?
See “What engine oil do you recommend?”

More on Penrite products:

HPR 30
I checked out the HPR 30 (20w-60), which seems like a reasonable alternative to the classic 20w50 I am currently using. More information here:
http://www.penriteoil.com.au/engineoils-products.php?id_categ=1&id_products=4
Specifications here:
http://www.penriteoil.com.au/pis_pdfs/HPR%2030%20MAY%202012.pdf

CLASSIC LIGHT
More information here:
http://www.penriteoil.com.au/products/vintage,-veteran-&-classic/classic_engine_oil_light
Specifications here:
http://www.penriteoil.com.au/pis_pdfs/CLASSIC%20ENGINE%20OILS%20Feb%202012.pdf

I have today (Oct 16th, 2012) received information from Statoil and ExxonMobil as well, about their recommendations and view. All good answers, but I need their confirmation to quote them before posting. I found the answers and feedback from all companies very positive and interesting.

Statoil

Oct 19th 2012
The reply from Statoil was written in Norwegian, so I have made a summary of this in English.

In general the reply points out that the Zinc, used as an anti-corrosion/lubricant, has been exchanged by better additives doing the same job (even better). Further that the materials used in modern engines are better, and can handle a thinner layer of lubrication film, which newer, thinner motor oils provides.
Most people would prefer thicker oil on an older engine; to get best possible lubrication, and it can also help to get the oil pressure up.
Statoil recommends their mineral ClassicWay product line, the 15W-40 or 20W-40 oils would work fine (but if your motor is happy with this viscosity). Both these oils are pretty high on Zinc; about 1500 ppm, and fulfill the API SL requirements (which is higher than API SE requirements).

When it comes to running-in oils, Statoil does not have any specialized products for this, but recommends a high-Zinc oil without additives to modify the friction in any way.

Comma

October 24th, 2012

The answer directly quoted as written by Comma Oil & Chemicals:
"
The difficulty with running in oils is that most engines nowadays don’t need them so few people actually produce them. Where running in oils are required, particularly in older applications, they generally tend to be straight mineral oils which from our range would probably be something from our classic range of products. Products of this type are favoured because of the absence of additives which can interfere with the running in process. Unfortunately I don’t know exactly what the requirement is for running in the vehicles in question so you would need to consult either the manufacturer’s original instructions or a expert that specialises in these engines.

Generally speaking, older and classic vehicles tend to benefit from being lubricated by the kinds of oils that would have been around at the time they were produced. This is particularly true with very old vehicles where the higher levels of certain additives in modern oils can interfere with the normal operation of the engine. Again we would usually start with the manufacturer’s original specification and go from there. Our Classic range of oils is designed to cover the requirements of older and classic vehicles and in the main these are the kind of products that found in vehicles produced in the early 60s and before.

There are some examples where older engines do benefit from the use of more modern oils. Certain designs based on flat tappets were notorious for wear in the valve train and to combat this engineers came to rely on the very high levels of anti-wear additives that used to be present in the oil technology of the 80s. Here, the high levels of ZDDP that were used provided excellent protection against wear to offset against the weaknesses of certain designs and materials. Over time legislation has driven down the amount of additives that are used in engine oils making them much harder to get hold of. One important thing to bear in mind here is that these oils would probably have only been used after the event – originally these problematic engines would have been lubricated by products that would have been available at the time like our Classic range of oils. Trial and error would probably have determined that more modern engine oils provided a benefit in these problematic engines.

In circumstances where protection against wear becomes the primary concern over all other factors then you may want to use something that is slightly higher in specification than a Classic grade but you should still be mindful of the original manufacturer’s specifications, particularly viscosity, and other design features of the engine that may be intolerant of the properties of more modern engine oil - the absence of full flow oil filter for example. Unless you have a specific reason to do so, I would not use very high performance products in these engines as the very low viscosity and high detergency of such grades can have some undesirable effects.

Unfortunately in older vehicles its not an exact science. More advice might be available from owner’s clubs or enthusiasts websites and forums for the particular marque in question. Experience is probably more use than theory when it comes to cherished vehicles.
"

Royal Purple

October 26th, 2012
Thor Johansen, Royal Purple
"
Thank you for requesting information about our Royal Purple motor oil.
Our motor oil labeled HPS (High Performance Street) do contain richly with both Zinc, Phosphor and ZDDP. (..)

We do recommend the use of our motor oil in vintage cars. When these cars were made they had not reach that far in chemistry as they have to-day regarding lubrication. "The best in lubrication is the best in any application involving friction.

Do your motor oils contain zinc and phosphorous?

Yes. All Royal Purple engine oils contain the zinc/phosphorous compound zinc dialkyl dithiophosphate (ZDDP) and are suitable for both roller and flat tappet valve trains.

Can your oil be used with flat tappet cams?

Yes. For stock or mildly modified flat tappet valve trains (<.525” lift), we recommend our SAE 10W40, 15W40 or 20W50 engine oils. In applications with flat tappet valve trains using high-lift cams and/or high RPM applications, we strongly recommend upgrading to our XPR line of engine oils as these have an even greater concentration of ZDDP providing excellent protection with the higher spring pressures. For a viscosity recommendation, contact our Tech Dept. at 888-382-6300.

Can your motor oils be used in older engines?

Yes. Mileage and/or age is not a factor when used in a mechanically sound engine. In high-mileage applications, we do recommend running a minimum of two short (3,000 mile/5,000Km) intervals before extending the oil drain intervals. This will enable Royal Purple’s high solvency to remove existing deposits gradually; such deposits can restrict oil flow, if excessive, as well as reduce the oil service life significantly.

Is Royal Purple synthetic motor oil?

Yes. Royal Purple Motor Oils are composed of a proprietary formulation of synthetic base oils and synthetic additives containing iso-paraffinic diluents.

"