Lubricants

This is an interesting question, as you point out thermal loads of equipment have increased, not just because of the increase in engine outputs, but also the emissions equipemt that is being equipped is increasing thermal load.
The isue is that the ideal temperature range of fluids has not changed, so it is an ongoing battle of OEMs to ensure that their designs do not increase the temperatures further, hence the increasing number of cooling matrices on a modern vehicle.
The IDEAL temperature for a fluid is set by the temperature in which the antiwear and oxidatant additives become active, too cool and these reain dormant, too hot and they do not perform adequately, this is in the ares of 75 - 120C. The other are for consideration is the performance of the base oil itself, Synthetics and partil synthetic handel hot temperatures far better than minerals, so for temperatures above 90C for prolonged times then a synthetic makes more sense.This is an interesting question, as you point out thermal loads of equipment have increased, not just because of the increase in engine outputs, but also the emissions equipment that is being equipped is increasing thermal load.
The issue is that the ideal temperature range of fluids has not changed, so it is an ongoing battle of OEMs to ensure that their designs do not increase the temperatures further, hence the increasing number of cooling matrices on a modern vehicle.
The IDEAL temperature for a fluid is set by the temperature in which the antiwear and oxidant additives become active, too cool and these remain dormant, too hot and they do not perform adequately, this is in the area of 75 - 120C. The other are for consideration is the performance of the base oil itself, Synthetics and partial synthetic handle hot temperatures far better than minerals, so for temperatures above 90C for prolonged times then a synthetic makes more sense.

Although the new API CJ4 product is fully compatible with the older CI4plus specification, it is never recommended to mix oils of differing performance levels, as it could compromise the performance of the product, this is particularly important with these new products as addition of non CJ4 lubricants could affect the exhaust after treatment life of 2007 vehicles.

TBN is a measure to determine the engine oils ability to withstand attack from corrosive components (Acids) formed by combustion of the diesel, a higher TBN means better protection from corrosion
There are two types of acids that are formed in the combustion of an engine, sulfuric acid from the sulfur in the fuel and nitric acid from the NOX. ULSD has seen a dramatic reduction of sulfur in the fuel, which should result in reduced sulfuric acid; however EGR rates have increased dramatically which will result in higher nitric acid components. The decrease from ULSD is smaller than the increase from EGR, resulting in TBN being as important now as ever.

Supplemental additives can disturb the careful balance of specialist additives that are in a modern lubricant to control deposits, viscosity, oxidation, wear, corrosion and base oils, too much of any of these components can cause a detriment to the performance of the lubricant. The use of any supplemental additives is consequently not recommended.