Morris Minor Owners Club

Hi everyone

I've been given some Castrol GTX 15/50 motor oil. Would this be ok to put in my 1964 Morris Traveller? It has a lead free recon. engine fitted in 1970.

Thanks
Ann

Hi Ann. It would PROBABALLY be OK - I would use it if stuck. but 20w50 is the ideal.

20/50 is more suited to older engines. The lower number refers to the viscosity when cold so if the engine is in good condition it should be OK .....
Explanation here http://www.upmpg.com/tech_articles/motoroil_viscosity/

40 grade oil is too thin for these engines! Your 15W50 is ideal especially in winter.

Hello all,

Thank you for your advice, I'll give it a go!

Ann

Once the engine is warm it makes no difference. The lower start-up viscosity will mean that oil will be delivered a fraction sooner. Unless the engine is very loose it should be fine.

Here in Canada and the US we depend on 15W50 that is meant for diesel engines because it includes a vital ingredient that has been legislated away in regular motor car lubricant. Lacking this ingredient (ZDDP) the flat tappets in our classic British cars tend to fail. <http://www.macysgarage.com/myweb6/ZDDP.htm>

I used 15/50 on my Traveller on occasion and it has been absolutely fine.

If there were any ill effects they would be so long term that you would not be able to identify the cause anyway.

15/50 is fine for uk - we used 20/50 as a 'standard' because it was easier to make (cheaper) than 15/50.
In reality you won't notice a difference unless the temperature is -10°C or less. In this case the 15/50 will be better.

however - this does not mean that 15/40 is ok - this is thinner when hot, therefore not good for an A-series

rayofleamington wrote:1-snip-
In reality you won't notice a difference unless the temperature is -10°C or less. In this case the 15/50 will be better.
-snip-

Would have been good for running one's Minor last winter and possibly this one as well!

Darrell, where are you getting this 15W50 from? Here in the west we use 15W40. I had never heard of 15W50 so I googled it and came up with "advanced performance synthetic engine oil" for racing, (by Mobil-1and also Amsoil), some Shell Aviation oil and some stuff in Mexico.

katy wrote:Darrell, where are you getting this 15W50 from? Here in the west we use 15W40. I had never heard of 15W50 so I googled it and came up with "advanced performance synthetic engine oil" for racing, (by Mobil-1and also Amsoil), some Shell Aviation oil and some stuff in Mexico.

OOPS I remembered big. You are right it's 15W40. The ZDDP is the important bit for your tappets. I buy the oil at Walmart, believe it or not. They cater to farmers and such that run a lot of diesels.

Now - I'm going to say something that will prompt a lot of discussion/disagreement. Unless your engine is in really terrible shape you should use a lighter grade of motor oil, multigrade of course. More engine wear occurs during the first few seconds after start-up than in hours of regular running. Thinner oil is distributed faster to where it is needed. As long as your engine has reasonable oil pressure 10W30 or even 5W30 should be OK. My 1950 side valve is currently running a salvage yard engine while the other block with the Alta head is awaiting attention (head gasket problem). It pops open the pressure relief valve at about 60 PSI on start-up, runs at 40 to 50 PSI warm and idles at about 20, and it's doing this on 10W30 oil. Of course not every Minor has a pressure gauge to tell what's happening but I seriously doubt that any of them really need 50 weight oil. They do need ZDDP or an equivalent additive to protect flat lifters. Refer to the link in my earlier message for the full story on this. BTW, I don't know if this applies outside North America, apparently ZDDP is harming catalytic converters so they just decided that old cars don't matter and changed the motor oil formulation.

I await the bombardment

The '15' bit (or less!) is what matters in a cold start - so yes - that's a good idea, although '20' is fine in normal UK winter. The second part - '40' is too thin (actually low on viscosity) at running temperature for decent oil consumption on these rather 'crude' A series engines. You really DO want 15W/50 (or 20W/50) for an A series in the UK. Yes - use 15W40 if you will - but the oil consumption will suffer - especially so in summer.

Well, I'd better climb down on this one. I went looking for some "expert opinion" to back me up and could find not a thing. Things have changed a bit in the 20 years since I retired from the auto industry, or maybe the old brain cells have slipped another cog. I don't have to yield on the idea of thin oil at start-up and I found good support on ZDDP but on the higher number, the 30-40-50 of the multigrade, Roy, and the high priced help disagree with me. I guess it's never too late to learn

Darrell

I understand what you are saying about 15w40 being to thin in summer, but I have been using Castrol 15w40 (previous bulk purchase) in my minors for 10 years and haven't had any problems / very low oil consumption. Also the engines haven't been reconditioned i.e seals or piston rings etc.

In the beginning - there was Castrol XL SAE 30 oil - and Castrol XXL SAE 40 oil. The heavier 40 oil was designed to help reduce oil consumption on older engines - but being more viscous - it made the engine difficult to crank when really cold. So the clever clogs at Castrol (and elsewhere!) put their heads together and came up with special twin rated oils - thinner when cold - but still just as 'thick' when hot. This was a great success - and was expanded by Duckams (I think at first) into the 20 W 50 oil they became 'famous' for producing. This was then expanded further into the wide ranging oils available now. I believe there are 20W60 oils - and there are certainly 0W30 oils because that's what I put in my 'modern' cars engines! I would never consider putting 20W50 in the modern - and equally the 0W30 would be useless in the classics!

these rather 'crude' A series engines

Interesting that you call these engines crude.

In the Model T Fords, built between 1908 and 1927 the engines had no oil pump, they simply used the splash system, with a little bit of help from the flywheel to move the oil from the rear to the front of the engine, yet the recommended oil is equivalent to #10. (Yes, the transmission is in a common sump w/the engine.)
Nowadays a lot of the owners (self included) use 10W30 because it's much more readily available than straight #10.

I did buy 2 of 5 quart jugs of 20W-50 when I was in Texas a few weeks ago as 20-50 is almost imposible to find around here. 15W40 sounds like a good substitute for me to use in our Morris when the 20-50 is used up.