Synthetic Oils

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Synthetic Oils -

Are they Worth the Cost?

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Today we hear a lot of terms thrown around when discussing motor oils. Much of the time, they are being used incorrectly.

So let’s start with mineral oil, this is the oil most of us have used in one form or another since the internal combustion engine was created. Mineral oils are distilled from crude oil as part of the refining process.

There are three categories of mineral oils; Paraffinic, Naphthenic, and Aromatic. Mineral oil can be as simple as baby oil, or as complex as today’s heavy duty motor oils. The chemistry used to create multi-grade oils and pickup and hold contaminants in solution is extremely complex.

Synthetic – Synthetic Oils can be created from many different sources and can offer many helpful characteristics such as lower friction, better high temperature performance, better stability, better sheer stability, better cold start lubrication, reduced oxidation, improved protection against thermal breakdown, less tendency to form sludge, reduces evaporative loss, potentially extends drain intervals.

There are two main categories for synthetic oils the first is:

 Polyalphaolefin (PAO) an American Petroleum Institute (API) Group IV Oil Base Oil and

The second is:

 Synthetic esters an API Group V Base Oils ((non-PAO) synthetics, including alkylated naphthalene’s, alkylated benzenes, diesters, polyolesters, polyglycols etc.)

There is also a category called Semi-Synthetics – a mixture of petroleum and up to 30% synthetic base oils. The name Semi-Synthetic is a misnomer, oils are either Synthetic or not. If they are a mixture then if you subscribe to the theory that a chain is only as strong as its weakest link applies and the mixture will only be as good as worst performing part of the mineral oil.

The primary reasons to change motor oil are because the oil gets dirty and or because the additive package in the oil gets used up. Dirty can mean physical dirt from the environment, soot from combustion, left over combustion products and a nearly endless list of contaminants. The additive package provides friction reduction, neutralizes acids, holds contaminants in solution, prevents oxidation, prevents corrosion, and many other vital functions. The additives are consumed or used up over time and they need to be replenished or failure will result. The method most often used is to replace the oil. This method has the advantage of taking many or hopefully most of the contaminants out of the engine with it.

Synthetic Oils may or may not have super additive packages, but eventually the oil becomes dirty to the point that it needs to be filtered or replaced and the additive package replenished or again replaced. The problem is that synthetic oil becomes contaminated long before it is “worn out” and has to be replaced to prevent damage from the contaminants. This means that often you are unable to take full advantage of the superior chemistry and characteristics of synthetic oils. When this happens the cost disadvantage of the synthetics outweigh its other advantages.

In situations of extreme cold, high heat, high loads, extended operation at high rpm, and other related situations synthetic oils offer many superior characteristics that may improve operability, increase engine life, provide better fuel economy, and potentially improve emissions.

However for the average grocery getter or most vehicles in normal operation the added cost of synthetic motor oil is probably not justified.

Please post your comments, thoughts, ideas, and suggestions.

Diesel Doctor

Copyright 2009© - William Richards


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Last modified: 04/06/09
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