Engine Oil - What you need to know

Posted by David Alkire on May 5th 2021

Today on Tech Tuesday in the First Place Auto Parts Studio we are going to take a look at a fluid that most car owners take for granted and don’t really understand what it does.

Hi guys, David here and today we are going to take a look at some things that you might not know about engine oil and explain what it does inside your engine and why its needed to keep your engine from going bang and kaboom.

For something that comes in such simple packaging, engine oil has multiple complex purposes when inside your vehicle’s engine.

  1. The first function and the one that most people are aware of is that Oil lubricates and reduces friction between moving metal parts such as pistons and the cylinder walls, the timing chain and valve lifters to name a few. Without oil, many components inside your engine would seize up solid. Without clean, filtered oil cylinder walls would get scored and bearings would prematurely wear and grove. Clean oil, and in the proper capacity is the lifeblood of your engine
  2. Next, it provides a protective barriers between the bearings in your engine such as the crank and rod bearings. The crank shaft in your car needs to securely be held in place as the pistons go up and down and yet it needs to be able to spin freely thousands of times a second. Engine oil cushions & fills the gap that has to exist between the crankshaft and bearing. Engine oil viscosity and that gap that exists between bearings and rotating assemblies like the crankshaft and camshaft is one of the combinations that helps control oil pressure. Too thick and the oil won’t flow fast enough and cause damage, too thin and it doesn’t provide the correct “cushion” and is a sure path to low oil pressure. Pay attention to your vehicles manual or your engine builder when it comes to what oil viscosity your engine calls for.
  3.  Engine oil also contains detergents to help reduce sludge build up that takes place due to the combustion process and in particular when short trips are taken where the engine does not reach operating temperature for an extended period of time. Engine oil has to reach temperatures of 180+ degrees or more before it can begin to burn off the condensation that builds up inside the engine. Short trips or starting your hibernating muscle car for short periods of time will create unwanted sludge build up inside the engine.
  4. Finally, engine oil helps carry away heat and contaminants from engine parts as it circulates through the oil pan and oil filter. In the past, if you built a high horsepower engine you probably installed what was called a “deep sump” oil pan and a high pressure/high volume oil pump. A deep sump oil pan hold more oil and the high flow oil pump would keep a greater volume of oil in circulation which helped keep oil temperatures in control. Oil temperature control is so important that many modern cars and trucks come from the factory with oil coolers already installed.

Engine oil is rated by its viscosity which refers to how easily an oil will pour or flow at a specific temperature. Thinner oil flows easier at lower temperatures and have lower viscosity and thicker oils have higher viscosities. The viscosity index measures the oils ability to resist changes in viscosity as temperatures changes.

An oil can be a multi-weight rated or rated as a straight weight.

Multi-weight oil, for example 5w-20, is rated for both its cold viscosity and hot viscosity. The rating is displayed on the bottle and gives an indication of the oils viscosity or its ability to flow when the oil is both cold (before start up) and hot (after use).

The first number is the oils cold rating and is followed by a “W” which stands for “Winter”. A lower first number is required when temperatures are cold so that the engine oil can flow and lubricate all the moving parts on start up. If you have ever had a thicker oil in a car, say a 20w oil, and heard the lifters or rocker arms rattle at start up until oil flow reaches them you will know exactly the effects that a slower flowing thick oil has on a cold engine.

The second number after the “W” is the oils viscosity at an engines “hot” operating temperature. The higher the number the thicker the oils viscosity is when hot. Multi-weight engine oil is the jack of all trades when it comes to engine protection unlike earlier single weight oils such as the 30 weight oils that were popular in the 1930’s & 40’s

If you have an engine in your car or truck that has a flat tappet camshaft you should be aware that due to EPA mandates due to catalytic converter contamination, oil manufacturers have reduced the amount of zinc in modern motor oil. Zinc was a high-pressure additive that was effective in reducing friction and wear on the camshaft lobes which is where the valve lifter rides on. When Zinc first started to be reduced there was a substantial increase in the number of camshafts that had worn lobes even after proper cam break in. Roller lifter camshafts like those found in modern vehicles has all but eliminated the issues caused with low Zinc motor oils but if your classic muscle car or hot rod still has a flat tapped camshaft, what do you do?

Specialty oil manufacturers have stepped up and are producing an additive named ZDDP that can be added to oil to increase Zinc level and protect critical high friction engine parts. Most of these additives are simply added to the crankcase at oil change intervals (being sure to maintain the correct total oil volume per your manual or manufacturers specifications). If you have a flat tappet camshaft, you should consider this additive part of your normal oil change procedure.

Conventional or Synthetic…the age-old question!

Conventional engine oil uses mineral oil as its base that is the same as it was when it was pumped out of the ground as natural gas or crude. Once above ground, the various oil manufactures refine and add their special additives to reduce wear, sludge and friction. Conventional engine oil has served the internal combustion engine very well for many years however there isn’t a limitless supply of it and the pumping and refining process has its own sets of environmental risks.

Synthetic engine oil is an oil that has gone through a chemically engineered process where the oil molecules are more uniform in shape and have fewer impurities compared to conventional oil molecules. Additional benefits includes a higher resistance to oxidation which is important when storing a vehicle for a long period of time and performs better in extreme high and low temperatures. Synthetic oil outperforms conventional oil in every category other than price.

Engine oil is a critical component of the proper maintenance for your classic or late model car or truck. It doesn’t matter if your car is powered by a traditional Chevrolet small or big block, a Chevy LS, a Mopar Hemi or a Ford Eco-Tech engine, using the correct oil viscosity in the correct quantities will help ensure that your Camaro, Mustang, Challenger, Chevelle or Nova performs at its highest level for many miles down the road.

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