Used Oil Analysis

UOAs are a great tool in the Management of any machinery that uses liquid lubricants. Unfortunately, their real value is often misunderstood by those who contribute to BITOG.

Firstly, it is important to realize that you get what you pay for. The most common forms of UOA are limited in their scope. It is a case of if you pay more you get more. So my comments here relate primarily to the “simple” UOAs – the cornerstone of those appearing on BITOG

Secondly, it is easy to assume that by carrying out a UOA you will be able to determine how quickly the engine is wearing out. As well, if you change lubricant Brands you will be able to compare the wear metal uptake results and then make a balanced best lubricant choice to make your engine last longer.

Sadly that logic is seriously flawed.

Single pass (random) UOAs will provide some information regarding wear metals but unless you have a history of your engine’s performance up to around 1 million miles the results are simply that – UOA results! As an example a limit of 150ppm of Iron is a reality – after say 100k it means the lubricant should be changed and all is well. But what is the situation if you have 150ppm of Iron at 5k? Where would you look what would or could you do? So UOAs are really a diagnostic tool – one of many!

The other parts of the UOA Report will be much more valuable to you – it will tell you about the CONDITION of the lubricant and its suitability for further use. This will enable you to get the maximum safe use from the lubricant saving a valuable resource in the process.

With some knowledge and experience you may be able to determine if you have a fuel or cooling system problem – and you will be able to see the level of potentially damaging contaminants such as silicates, soot and etc. You may be able to monitor the levels of additive depletion too. In a low use engine the TBN (if taken) will seriously indicate if the lubricant is still able to minimise corrosion and its effects and this will help to prevent cam lobe pitting etc.

During the last 50 or so years I have carried out hundreds of UOAs on all sorts of engine configurations – and on transmissions, gearboxes and differentials. These were done in consort with four Major Oil Companies (Shell, Exxon-Mobil, Castrol, Chevron-Caltex), my Employers, my Customers and on my own Fleet and other vehicles. Not once were they ever used to discriminate one lubricant from another on the grounds of wear metal uptake!

In my case correctly interpreted UOAs have saved the odd engine from major problems and have proven that certain viscosities work better than others in some specific engine families. UOAs certainly optimized the service life of the lubricants in a cost effective way for many of my customers

The “dream” that engines may be constructed with “traces” built in to key components with their known “wear-down” limits enabling replacement has not yet become a reality in the Automotive world. As new technologies emerge it may now never happen at all in the real World

UOAs are of course notoriously unreliable in predicting “sudden” failures!

Manufacturer’s lubricant Standards, Approvals and Lists (Approvals)

Manufacturer Approvals (as we’ll call them here) have been around for at least seventy (70) years. The first real Approval “Standards” came from CATERPILLAR and later, the US Military. The MIL’s Standards will not be discussed here. Others Standards existed then too but are hard to materialise now

German engine makers and the Aviation and Shipping Industries formulated specific performance requirements for the various lubricants used by them in their increasingly complex machinery

Now, in this modern Automotive age, Approvals have become a way of life! We may ask why?

Manufacturer Approvals commenced in order to ensure that the specified lubricant met their minimum performance standards and Approval was Brand neutral. For instance the CAT Series 3 Standard and its various Supplements were met by many Brands Worldwide and for many years

In the 1950s Mercedes Benz produced comprehensive Service Booklets with many Approved lubricants Listed (Brands, types and nomenclature) from some quite numerous Suppliers

So as technologies have become more complex and emission controls more demanding the need for lubricants with very specific qualities has become mandatory. Many actuators and components within the modern engine demand the lubricant to be of a known quality with reliable characteristics both cold, hot and for extended periods too. Extended Warranties often leave the Manufacturer exposed for up to five years and for great distances as well. In the case of trucks this can be out to 1m miles! Therefore their liability is enormous and the need for known operating parameters is paramount!

Mostly the Manufacturer’s Approvals are based on the Quality Test protocols of the API or ACEA – or both. These protocols are largely based on specific engine families from many Manufacturers and they have well known characteristics that are very important in lubricant formulation The Manufacturers then extend or modify those Test protocols and perhaps introduce others that are known factors in their engine families and their durability. Many concentrate on such things as HTHS viscosity, anti foaming and viscosity retention – sometimes out to 1000hrs!

Many modern engines have unique lubricants as their Factory fill and in some cases a special specification lubricant many be needed for the first 100k miles or so. This is for specific “bedding in” reasons and often depends on the engine’s design and certainly on its “wear face” metallurgy! People that chose to ignore the Manufacturer’s advice concerning the first oil change period and the lubricant to be used then are IMO quite foolhardy – especially if they intend to keep their vehicle for many years

Of course the validity period of the Approvals is known and the permission to change the lubricant’s formulation is dependent on the “percentage” of change, otherwise a retest is required. Some lubricants may be withdrawn from sale during the period – others are rarely added. Mandatory changes are also likely to be based on the Warranty experience from the Manufacturer and this is usually taken up via a transparent shift within the Approval’s criteria

So the advice I give to all BITOG readers is to use a lubricant of the correct viscosity that is specified by the Manufacturer and Listed by them as Approved – especially when under any form of Warranty

As for Manufacturers and Oil Companies being in collaboration – well that may well be so. However take Porsche – they have about 100 Approved lubricants Listed – they Factory fill with Mobil 1! They also work very closely with Mobil’s Engineers on engine development but the car’s owner can use any of the 100 lubricant with confidence – simple as that!

VW-Audi and BMW work closely with Castrol, Ferrari with Shell – the technical benefits to both parties are enormous!

The benefits to us as an “end user” is a reliable product that has the utmost durability during its design life.

Doug Hillary

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