Question: Lots of people have been talking about "synthetic oil" and "oil additives" -- what do you think is best for my new car?

Answer: Oil is blood of an engine and like the blood in our own bodies it does many things. It seems to be a popular belief that if high priced synthetics are used in an engine that oil changes can be further apart and a huge increase in power/efficiency will be experienced - - NOT QUITE!

Remember oil just doesn't lubricate - - all oils whether mineral or synthetic have what is called an additive package mixed in with them. This "package " is a bunch of chemicals that allow the oil to its other jobs! and it is the additive package that wears out not the base oil. No matter what the main constituent of the oil is (synthetic or mineral) approximately sixty percent of what is in the container is additives. The length of time that it takes for the additives to die off varies and is primarily dependent on the type of service the engine sees and to some extent what the oil was to begin with (how expensive). This length of time difference however on the additive package life is not huge.

So in other words all oils are not created equal but all of them wear out in roughly the same length of time as the additive package de-pleats. The bottom line is that the more oil changes the better for an engine (within reason) no matter what the marketing propaganda says. If someone feels better spending big $ on more expensive oil GREAT!

Now one caution - - you also get what you pay for so if you drive something upscale or really care about the longevity of your engine spend at least enough to get a good quality product or good name brand, don't use bargain stuff.

SYNTHETIC VS MINERAL

The difference is the molecular make up of oil synthetic of course being man made has a very consistent sized atomic makeup which can give the oil very good and consistent properties, the mineral oil on the other hand has a lot of different molecules in its makeup. The synthetic then potentially has a more uniform make up so its properties can be controlled therefore we see these wider range applications 10 w 50. Is this better? Sometimes!

For the explanation lets talk a bit about oil basics the two numbers either side of the "W" are viscosity indicators, the lower the number the more liquid or watery the oil, and of course the higher the number the thicker the oil. We need thinner oil when the engine temperature is low particularly in the North American climate, and the thicker oil when the engine is up to temperature for its lubricating power. A 50 weight oil in sub zero weather looks more like grease and the lubrication system of an engine is incapable of delivering it to the places in the engine that it needs to go to when it is this thick. This factor is what stimulated the development of multi-grade oils. So our 10 W 50 oil then has the viscosity of a cold 10 oil and the lubricating power of a 50 oil when hot . The one remaining symbol is the "W" this means winter and is a key factor in the additive package, it means that the oil additive package has chemicals in it that help it survive water contamination which is a result of condensation a phenomena caused by the dramatic heating up and cooling down of the engine in these type of conditions. Is it better?

Only if the engine is designed to run on the sometimes low viscosity of the 10 oil and consistent sized polymers in the oil. If the engine has been designed to run on molecules that are inconsistent in size than it is not better it may be only "as good as" and better is a mineral oil with its multi sized molecules. The clearances in between the engine moving components are designed to allow the oil to flow through these gaps and keep the metal parts from touching and wearing each other out . Using and oil other than what was designed to be used could then affect the oils ability to go where it has to and maintain a protective film where it should. Therefore putting new low viscosity synthetic oil in an engine designed for high viscosity mineral oil may cause a problem, but putting high viscosity mineral oil in an engine designed to run on synthetic could also present a problem.
Advertisers are not engine designers they design brochures to make people think that they are getting better value or in some cases something for nothing. Go by the manufacturers recommendation they designed and extensively tested the engine.

ADDITIVES (snake oil)

It is always easy to design some test to show how some off the shelf additive will enhance the oils ability to do one thing well. The problem is that the oil has many jobs not just one and some of these additives could actually hamper the oils ability to do the rest of the things that it needs to. The oil has to carry away wear particles, control acids that form when combustive residue mixes with water from condensation, it has to allow heat transfer it has to deposit anti wear particles like Teflon onto the moving surfaces, it has to be able to handle hydrocarbon dilution from unburned fuel deposited on the cylinder walls etc. etc. Most oil manufacturers of lubricating products will tell you that the oil already has things in the additive package to help the oil do what the snake oil salesman says that his Brand X oil elixir will do anyway just that it is a balanced quantity with the other additives in the " Additive Package" so that the oil can fulfill its entire job function.

Severe Service

For severe service applications the oil should be changed more frequently. Operating the engine out of the designed operating range breaks down the additive package more quickly. The more frequent the occurrences the harder it is on the additive package because some of the additives are aimed at helping the oil deal with less than perfect operating conditions. This doesn't just mean people that drive the vehicle " Hard", oil is meant to do its job under normal operating temperatures anything that effects the normal heat that an engine develops is severe service, short trips to the store just around the corner can be just as hard on the oil and engine as someone with heavier than normal shoes because the engine does not get up to operating temperature where it is designed to operate. In a situation where someone is a more aggressive driver or in fact races their car the contamination to the oil is totally different than the case of the " Sunday driver" this activity in particular raises the hydrocarbon dilution of the oil more than any thing else and actually reduces the oil viscosity. Hydrocarbon dilution is a result of unburned fuel being deposited on the cylinder walls, which is a result of dramatic throttle application. So each type of severity effects different things in the additive package but the net result is the same the frequency of replenishment of the additive package and the elimination of the waste materials created in the oil by the operation of the engine must occur more frequently.

Summary

Change the oil at or before the recommended time specified by the vehicle manufacturer, the more severe the service the more frequent. Use the type of oil the engine is designed to operate on.