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Getting greasy: Oily bits Part 2


After some phenomenal feedback from our previous ‘Oily Bits’ piece we decided to publish the follow-up sooner than expected. The majority of the comments and queries surrounding the article were about high-mileage oil. So let’s start with that as a subject.

We defined high-mileage oil as being a product that one makes use of when their car is a bit older, specifically when the engine is showing signs of age. But before I start with more information on high-mileage oil let’s explore the potential signs an owner should look and listen out for when determining whether or not their vehicle is in need of high mileage oil.

The checks

Check the underside of the car for oil leaks and if your vehicle has a piece of pop-riveted plastic covering the underside of motor and gearbox take that item off and inspect for potential leaks as these covers often mask hidden dripping Also take note of the sound your engine is making, if it’s louder than before or is making a rattling sound the motor could be in need of the conditioners, seal swells, detergents and wear/friction additives that high-mileage oil provides. Check if your vehicle is puffing blue smoke too as this could mean that your valve guide seals are worn, allowing oil to seep in to the combustion chamber, causing the blue smoke or in minor cases, high oil consumption.

Seals and non-metal parts

Remember that our cars are only machines, with materials in each motor being subjected to wear over time. Your engine not only features metals, but highly perishable items such as seals and other non-metal parts that will likely wear-out faster than the metal components in your engine. When these items begin to show signs of age it can lead to oil leaks and excessive oil consumption in addition to performance and fuel consumption problems. High-mileage oils make use of additives that help prevent further damage while in some cases fixing problematic seals and perishable materials in your engine.

All reputable oil makers have high-mileage oil on sale, just ask the sales person at your local spares shop for your preferred/recommended brand’s high-mileage option and then read about the various additives and detergents in this oil to determine if this is the lubricant for you.

Those number and letters

You may have seen on the bottle of oil that mechanics put in your car or perhaps the small top-up that you used at the garage a series of numbers on the oil can/bottle. These are really rather important. You see, you engine is a sum of moving metal parts that requires oil to protect these components from touching and creating friction and heat, which as we know, can and will kill your engine. The letters have to do with the viscosity of the oil (how thick it is) and how it reacts in both low and high temperatures.

The Society of Automotive Engineers (SAE) defines a numerical system for grading motor oils according to viscosity. The suffixes (0, 5, 10, 15 and 25) followed by the letter W designate the "winter" grade of an engine oil.The number before the 'W' is the 'cold' viscosity rating of the oil, and the number after the 'W' is the 'hot' viscosity rating.

The second piece of important information on the label is the API service classifications. The API service classification is a two-letter code starting with either an "S" for petrol engines or a "C" for diesel engines. However most manufacturers now specify whether it is a diesel or petrol oil or if the oil is suitable for both engine types

The second letter in the API service classification is very important as it effectively speaks to the model years the engine oil was formulated to serve. As an example, the first API service classification was "SA" and these oils were designed to meet the requirements of cars built prior to 1930. The API SA service classification was followed by SB, SC, SD, SE, SF, SG, SH, SJ, SL, SM, SN and so forth. By having a look at these letters we can see what oil best suits our vehicles.

We plan to speak to an oil expert for our next insert of Oily Bits and elaborate on what we have already covered. Please feel free to comment or mail us your oil queries at and we will do our best to address them in future inserts.


Article written by Sean Nurse
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