MG T-ABC

Having been recommended either Penrite or Morris oil for running in I note that Morris "Golden Film" is graded at SAE30 whilst Penrites` recommended grade is 15w-40. My leaning is to the Penrite. Any advice/suggestions please.

I don't think it makes any difference which you use. Probably just different names for basically the same thing. I expect it's al marketing. The important thing to decide is whether you want to stick with a mineral or synthetic oil and if you have a newly rebuilt engine do you go with a detergent multi grade or a traditional straight grade non detergent oil?.

In my opinion, If the engine is rebuilt (therefore clean to begin with) and you have a modern filter there is no advantage with straight 30.

No doubt the factory used clean (mineral) oil on the first fill.

If a superior oil - such as a synthetic multigrade - had been available, I guess the factory would have used it. My only reservation would be that modern oil has allowed engines to be built with closer tolerances and modern metallurgy has extended the lifespan of those engines. Whilst the oil is better, it is also thinner and that worries me especially as our engines are prone to leaks.

Duncan, whatever grade of oil MG used in the TC engines, it was certain to be from Duckhams. William Morris and A. Duckham shared a long-standing business relationship friendship together. Morris had a contract with Duckham to provide all the oils and greases for the various Nuffield companies (Morris, Wolseley, MG, Morris Commercial, Riley, et al). Morris received a quarterly commission on sales of Morrisol and its follower, NOL (Nuffield Official oiL). This commission was significant in amount.

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Tom Wilson

I've used Royal Purple break-in oil with good results. But I've also used standard oil for break-in with good results.

As for the synthetic debate... My take is that while synthetic is a superior lubricant, it's also far more expensive and one of it's biggest advantages, longevity, does us no good. Carbureted old cars like ours don't burn very clean compared to modern ones, so the oil gets dirty relatively quickly. You have to change the oil far more often than a modern car in order to get the impurities out, and this means throwing away expensive oil that still has lots of life left in it. I prefer to use a quality non-synthetic multi-grade oil and change it every 3-4,000 miles. Just my opinion of course.

Interesting, Tom.

If you use a high ZDDP engine assembly paste (easy to find) then you would want to avoid using a mineral oil marketed as having high ZDDP for intial fill/break-in.

Even a well tuned and freshly rebuilt engine will have blow-by into the crankcase. Lack of a PCV type (flow through) setup on the XPAG crankcase causes the oil to become acidic from those gasses much sooner than in a "modern" engine. Low operating oil temp. (150F) and even a trace of fuel contamination does not help. Result is sludge, which this engine is famous for. Simple solution is to change the oil often enough so sludge does not happen. I consider 2,000 miles pushing it. But each XPAG is different.

Operating conditions will greatly affect sludge as well. I was talking with some BMW guys back east and they all have major sludge issues. Whole valve covers get filled with the stuff. The west coast guys have zero such issues. Cold, wet weather is not a car engine's friend.

Out West, I have only ever seen sludge on the bottom of my XPAG sump. I scraped it off with a putty knife before putting the sump back on. Most people find it impossible to believe that someone could have a 73 year old factory built XPAG with work only ever being done on the head. If you are ever going to store an engine for a really long time, be sure it has got clean oil in there, first.