Rotella straight 30 Wt oil

[Gary - K7GLD]

Yes that's true..... but a straight weight has less additives... therefore it is preferred by "traditionalists".

NOT to be a nit-picker, but it's EXACTLY those "additives" that some want to minimize - I buy a lube for the LUBRICANT it contains - a bunch of other, NON-lubricant additives that might not be required for a specific application, and that dilute the percentage of actual *lube* in the can, are what some would like to avoid...

 

[jimnance]

I don't believe it would start. I don't recall ever seeing one with out one. But I was just a parts changer years ago on the 54/76/92/149 series. I hope them be the correct model numbers.



It wouldn't get a charge of air to compress and fire the air/fuel mix. The 149 has four turbos. When they begin to spool, the wate gate bypasses the blower becasue then it just gets in the way of air flow



I believe that you are correct about the Detroit. No argument there. It was designed from the git-go to have a blower. I was speaking in theory, not to a particular engine design. That's why I suppose it was nit-picking. Of course, most diesels of the era were Detroits.

 

[jimnance]

YUP - That's the way I understand it as well. Actually, in a constantly moderate climate, a single-weight oil should be just fine, and has lots fewer extenders and similar additives that are there ONLY to provide the ability to maintain viscosity stability at widely varying temperatures - and every ounce of an extender added to an oil REDUCES the actual lube content by the same amount!



And, there is no connection between detergency and whether an oil is straight weight or multi-weight...

I agree with you Gary. I think it's important to point out that there are several different types of additives added to engine oil. Viscocity modifiers are added to multi-weight oils to make a single weight base stock of low viscocity (15W) behave like 40W when it gets warm. These are the additives that are not necessary in a moderate climate where 30W can be used.



The other additives are friction modifiers, anti-scuff and anti-wear additives, as well as detergents. You will find these additives in all oils carrying the CI rating or any other modern blend for that matter. While the exact foruma may vary a bit from one company to another, they are necessary to meet the API spec. These are the "good" additives.

 

[Gary - K7GLD]

I think lots of guys would be surprised at the actual percentage of various additives used in today's engine lubes(close to 50% as I recall!). Sure, some of them are needed to cover the wide range of climates and usage of the engines they go into - but if *I* live in a moderate climate that exposes my engine only to routine warm up extremes, why would I want or NEED additives (OR expensive synthetics!) that are primarily there and benefit users in Arctic or Sahara type extremes?



Sure, some of the anti-foaming and antioxidant additives, etc. , are helpful - but in a moderate climate, "normal" engine operation and oil change intervals, the good quality single weights make a lot of sense...

 

[jimnance]

I think the number was shy of 50%, maybe 40%, but still a very substantial percentage.



Lube oil base stock by itself is not the greatest lubricant for our engines. The question is how much is good enough?



I don't know the answer to the question, but suspect that the number is pretty high. In general, as API ratings have risen the amount of additive needed to meet the specifications has increased. I think we know from the length of time an engine is now expected to operate that oil technology has improved. How much is the oil, and how much is improved engineering, metalurgy, and machining advances is open to question I suppose.



Even the new CJ oils have a very percentage of additives. I'm not positive, but I've been told that the percetage of additives in CJ has increased while the effectiveness of the oil may not be as good as CI. The really good metallic additives have been largely eliminated to avoid contaminating the exhaust emissions system. What replaces them is not quite as good. Also, the oil must be able to effectively suspend increased amount of soot and combustion by-products. In short, CJ oil is a compromise of sorts to meet all the needs of our new engines.



Frankly, I think the new CJ oil is adequate for our older engines, but not as good as what it replaces.



In aircraft, where suspension of combustion by products has always been a big issue the oils have not progressed very much. In fact, because of the risk of detonation metallic compounds have been avoided in these oils for years. Partly because of oil technology we have seen very little improvement in aircraft piston engine life. There are other reasons as well, but lack of advancement in oil technology has played a role.