Engine oil and the importance of good lubrication.

"Oil: Oils well that ends well."

When starting a cold engine let it tick over for a few moments to circulate the oil - most engine wear occurs within the first minutes of switching it on 

Oil is an often overlooked part of the engine but more internal friction = lower power and more heat produced.

So the aim is to reduce the internal friction and cool the engine with a good oil and changing the oil frequently is vital to add longevity to your engine - certainly for the paranoid before and after a track day session and every 3-6 months.

This is not intended to be a highly technical guide that bangs on about SAE's Viscosity index and shearing of oil (if you want that ask for it in the feedback box below!).

This is a rough beginners guide to the slippy stuff and enables you to make an informed decision when choosing the correct grade and type of oil for your car.

Which oil Viscosity should you use?:

Multi grade oils are popular and are rated typically with 2 numbers ie: 15w40 which shows

1) the thinness (viscosity or how runny it is!) at low temperature (W=Winter)

2) the thickness (viscosity or how sticky it is!) at high temperature (20w50 is thicker and 10w30 is thinner).

If the numbers are close together then the operating range and performance is more uniform. The second number is the important one unless you live in subzero climes! Use the recommended oil for you car - older cars sometimes prefer a slightly thicker oil to avoid leaks and burning in the cylinder but consult your workshop manual for your car.

Choosing oil that is too thin can cause permanent leaks in the seals. Running low on oil will typically wear the top of the engine and this wear is typified by a rattle in the top of the engine on acceleration especially when cold, the pistons will also wear more quickly and you will start to burn oil (well, your car will) producing a blue exhaust discharge.

Do not use a different grade to the recommend one unless the engine is very worn (in which case go thicker) or if the engine has been rebuilt (a thinner oil may be needed but the engine builder will recommend the correct grade.)

Never put a semi or mineral oil in a car that requires fully synthetic unless this is an absolute emergency and get the oil drained and corrected as soon as possible afterwards. Try also to avoid mixing viscosity grades of oil and certainly never mix oil types.

NB: The oil light comes on to tell you your oil levels or oil pressure is dangerously low and NOT when it needs topping up check your dip stick every 2 weeks or after a long journey - oil is CONSUMED by engines (but different cars have different consumption 16 valves seem to use more than their 8 valve counterparts) and always goes down - never up!

Some people recommend a thinner oil in the winter and a thicker one in the summer - your manual should have the recommended oil specs to air temperature chart. Sadly so many people just buy the cheapest oil they can get and use the Grade for the cars life summer and winter.

Which oil type - synthetic, semi synthetic or mineral?

A raging argument ensues about synthetic oil lasting for 36,000 miles or more. There is certainly some big advantages to synthetic oils but I would still recommend a regular filter change - the filter gets the tiny particles of metal from inside the engine that acts like a sandblaster inside your engine so even if the oil does last it will pick up lots of gunk from the engine.

While your changing the filter you may just as well change the oil anyway! Choose a good quality filter that collects the damaging small particles of metal. There are magnets available that wrap around the filter to collect more fine metal particles and these have be proven to be effective.

Engine oil Additives:

Most oils contain ingredients to resist combustion (stops engine fires!), detergents - cleans the inside of engines and anti cake agents to prevent the oil clogging up and blocking important bits of the engine. Some oils contain electrostatically charged particles (GTX magnatec, electrosynthtec etc) which bond low friction molecules to stressed metal surfaced, (crank journals, bores, cams etc) and help reduce cold engine wear.

There are additives that you can add yourself to the oil:
PolyTetraFlouroEthelyne - PTFE bonds to the surface of the metal parts to theoretically create a low friction surface. Other additives work in this way also and usually need the engine to be warmed up for the bonding to take place - most engine oils set out to do the same thing so the question of these additives has been raised.

(I have used X1 super lube and can vouch for it's effectiveness - it reduced cold start noise the engine ran cooler and I get slightly better fuel economy.) When you strip down an engine treated in this way the cylinders will generally have a hard black - almost mirrored finish - perfectly smooth. If you have a rattle from the top of the engine, sticking valves (especially if the cars servicing has been neglected) or cold start problems you may wish to give these additives a go - there is a chance the problem will not get any worse if you are lucky (avoiding an engine strip down).

Other substances condition the oil and make it 'sticky' (it works well and I don't know how!). The oil seems to cling to the surfaces of your engine for longer but it still lubricates and flows around and can even prevent minor oil leaks and reduce blow back and burning oil (Morays is the products name but I'm sure there's others around) The downside is that this additive is flushed out with the oil and needs to be reintroduced.

When starting a cold engine TorqueCars recommend that you let it tick over for a few moments (don't run it for minutes though) to circulate the oil - most engine wear occurs within the first minutes of switching it on although there is little if anything that can be done about this - as the oil warms an thins it gives better protection (most cold start engine wear occurs due to acids created in the combustion process rather than friction). Only drive at 1/2 to 1/4 of your redline until the engine warms up unless you want to wreck the engine.

Some pistons, normally high performance ones are tapered which stops slap on the skirt which can be catastrophic to a piston. An engine specialist showed me scratch marks on a piston (on the tapered end) and explained that it indicated that the car had been driven very hard before it had warmed up - obviously pistons change shape slightly (expanding) as they warm up and this design prevents piston slap.

The piston contains less metal than the bore surrounding it, which may even be made from a different material with a different modulus of expansivity, thus the piston is likely to expand at a higher rate than the bores. Until the whole engine is warm and the bore and piston have expanded equally engine revs should be kept relatively low.

Important note to turbo car owners:
Turbo's spin at phenomenal speeds and are more prone to wear if the wrong oil is selected. They also run at high temperatures and this can show up weaknesses in the oils formulation. Also if you have a turbo you must wait for the turbo's turbine to slow down before switching off the engine.

The supply of fresh oil stops when the engine stops and the turbo's spinning will continue and wear it out (consult your manual for details or buy a turbo timer which keeps the engine running for you automatically shutting it off when it's safe to do so.) Most turbo manufacturers recommend the use of a fully synthetic oil.

How much oil should you put in?

Obvious Tip: keep the oil level below the max and above the min line !! - too much oil and it will get into places it shouldn't and could start seals leaking or cause other damage the engine ie:- burning oil/broken seals/piston rings.

Too little oil will cause premature wear. Always change the filter with the oil. Of the 7 oil changes I had done at garages only 2 had the correct level of oil - (3 would have caused serious damage to the engine if I hadn't spotted it (when I drained it out there was a whole litre too much oil!) after a service check the dipstick and complain if the oil is under the min or over the max mark!

I heard recently about a Porsche which was burning oil - it had been overfilled. When the correct level was restored the car thankfully didn't burn oil and no damage was done. The dipstick (on this car) should have been checked with the engine running as oil seeps into the pistons when stationary!

Don't assume you know how to check the oil. Consult the manual. If the manual says 4.5l then put 4.5l in and check the level in the way specified in the manual, allowing sufficient time for the oil to reach the sump, then top up if necessary - generally oil is checked with the engine warm but having stood for a couple of minutes to allow the oil to settle. Although I have slagged off garages the average motorist is equally negligent with 1 in 4 having below the minimum oil level in the engine.

Please also note that only car engine oils should be used, not motorcycle oils, which are designed for a totally different purpose (they have to lubricate the gear box and also most bike clutches run in oil) - the same goes from transmission fluid.

To discuss engine oils in general or more specific engine oil selections for your car please register and join our friendly forum and our friendly community will answer your questions.

This article was written by Waynne Smith on TorqueCars, and I appreciate your feedback and suggestions. This entry was filed under Articles, Car care. You can leave a response below or join TorqueCars forum to discuss this article and car modification in detail with our members.

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