Triumph Repair: TR4A Engine Oil, castrol oil, sunbeam lotus

Question
QUESTION: Hi Howard,

In your learned opinion and experience, do you have a firm recommendation on motor oil:  brand, weight, synthetic vs. conventional?  I have a TR4A and the motor was rebuilt about 6,000 miles ago. I drive about 1,000 miles per year from April to November. I live in the Northeast. The motor runs fantastc with 65psi at  2000 RPM.

Generally I have been running a 15W-40 weight conventional. This spring all I could find in that weight was a diesel spec oil (API CI-4), which I thought was not bad considering it has higher anti-wear (ZDDP) than the new gasoline spec oils (API SM).  However, I have since developed some pretty major leaks in the engine. Could this be completely coincidental or possibly related to the higher detergent levels in diesel spec oils?

Cheers,

Bob
PS: generally I am very against any oil additives but, what's your opinion on these new ZDDP additives (ZDDPlus)?

ANSWER: Hi Bob,
I am not an oil expert but I will be glad to tell you what I do know. First I have no experience with the diesel oils except for working on a few VW diesels and I hated the oil they were using just because it had graphite in it and the oil was like ink and hard to get off of your hands and everything else.

I have worked for MG, Triumph, A-H, Sunbeam, Lotus, Jensen & Jaguar dealerships for many years and I found that 10w 30 for the winter and 20w 40 for the summer was what I arrived at for a recommendation for weights. Unless the engine was in need of a rebuild and then I would go up to a 20w 40 or such.

In these dealerships they used Castrol oil and talking to some Castrol reps at times I stayed with Castrol oil since. I'm sure that many of the other brands are good but I have no experience with them.

I have learned that all brands of oils use different additives to achieve different qualities they want in their oil, so it is very important not to mix brands of oils in an engine. Because each company used different additives and even the oil companies' engineers don't have a clue what you have made by mixing them.

The only additive I studied a little was STP. My younger brother received samples of STP before it was named and put on the market as STP. He was a tool and die maker and they were given it to test as lube to use on lathe centers etc. He was impressed with it.

I watched the sales rep for STP do some impressive demonstrations once where he showed that even though it appears think and gooey it will penetrate into a tight place that straight 10w oil can't get into. STP oil treatment was designed to help maintain the viscosity index of an oil. The viscosity index is the ability of an oil to maintain it's thickness (viscosity) when hot. All that was impressive to me but that is not why I started using it.

In the dealerships I worked in, we would many times build an engine and not get to put it in the car for days and sometimes weeks and  using just engine oil to lube all of the internal parts was dangerous because we found that engine oil runs off of the parts when sitting. So oil itself could not be used. Most mechanics used white lube to lube all the parts but I seen first hand what can happen there. A mechanic in our shop rebuilt an engine and put it in the car and he always started the engine to get the oil pressure to show on the gauge. (bad practice) Sure enough, the engine seized up and stopped. The service manager and most of the mechanics were concerned so we helped him pull it down and what we found surprised everyone. A bearing was seized up but a nice thin strip of still good surface was in line on the crank where the oil hole was.
After much talk we decided that the bearing clearance was a little too tight and that he had used a lot of white lube and it still had a plug of white lube in the oil hole in the crank. The new engine oil could not get to the bearing in time due to a air lock that the white lube had made and even though oil pressure had finally came up it was too late as the tight bearing had squeezed out the little bit of white lube on the bearing and because of the clearance the air pressure from the late oil pressure could not force enough of the plug of white lube into the bearing surface to save it.

Most mechanics used white lube because it would still be there a day or a week later when they would get around to installing an engine.
I did an experiment with STP and engine oil. I lubed a piece of metal with engine oil and one with STP and set them outside and left them there for a week and I found that the STP was still on the metal and the engine oil was not. So I started mixing 50/50 STP and engine oil to use as my assembly oil. Also because I had a small airplane that sat for weeks without being started I even added it to my airplane oil. But later found out my aircraft oil had it in it already. I used STP from then on in my cars just because I know it will still be on the metal if I don't start that car for a few days and straight oil will not be there even though Castrol oil has a small amount of viscosity index booster in it.

That's the best I can tell you,
Howard

---------- FOLLOW-UP ----------

QUESTION: Howard,

Thanks for the detailed reply. Very helpful. Just to be sure, were you suggesting the following:
10W/30 = Winter
10W/40 = Summer
20W/50 = if motor in need of a rebuild?

I'm curious to try the 10W/40. The 15W/40 I have been using gives perfect oil pressure when hot but, must admit the pressures get very high when cold. Perhaps the 10W will help bring that down.

Thanks again,

Bob

Answer
Bob, there is nothing wrong with what you are using. It is close to what I use, I just told you what I always used.

When they say 10w 40, they are saying the oil will meet the standards of a 10w oil but still work for a 40w oil. The way I related it to my students was to think of the number as a size of a ball bearing. A # 10 ball was a small ball and it will work well in a bearing that the #10 ball will just fit into. However, if you tried to install a #40 ball into the bearing clearance that fits a #10 ball, it would not go in and the bearing would seize up. But if you put a #10 ball in a clearance that normally takes a #40 ball it would bang back and forth until it did damage. So, when you have several different size clearances you need a multi grade like 10w 40 to fill all the needs. That is the way I got the point across.

The number is the viscosity and viscosity index is the oil's ability to maintain that viscosity when hot. The viscosity index is not usually on the can and has a different numbering system.
Howard