It’s Just Oil…

When I was a kid, I had an old Hyundai Pony that I drove around the potholed streets of a small town in Northern British Columbia. Body panels consisted of some steel, but largely Bondo and sheets of plastic cut out of old margarine containers. The engine was so worn out, the crankcase was filled with “Stop-Smoke”, a compound thick enough you had to warm it up if you wanted it to pour faster than molasses in an igloo! While that was not a big deal for a 300$ car, most people do not pay any attention to what goes into their engine. It’s just oil, right? Wrong. Lets take a quick look at some key differences.

Oil Pour test

1. Viscosity. This is the most obvious, but is often given little consideration. Does it matter? Absolutely. Ford had a common complaint of cold weather no-starts on their diesel pickups in the 1990s and 2000s, and the company linked it to wrong viscosity oil. They recommended a 10w30 oil be used in the winter months, but customers knew better…It’s just oil right? Until they couldn’t get it to start in the winter.  It matters. Engines are designed with clearances and flow rates for recommended oil weights. Always find out what the OE spec is for that engine.

2. Diesel oil vs Gasoline oil.  News Flash: One of these things is NOT like the other! While they have the same base oil, additives make the difference here.  Oils designed for Diesel engines have very high detergent levels,  which can cause issues for  gasoline or LPG engines. Their lubrication systems are engineered around a particular set of oil characteristics, and higher detergent levels can change these, such as the way oil behaves on cylinder walls. The other major factor is catalyst compatibility. Diesel oil has a high concentration of  zinc dialkyldithiophosphate (ZDDP), an anti-wear additive that can wreak havoc on the emissions controls on gasoline engines.  Diesel engines and emission controls are designed to handle these.  

3.  Synthetics. Probably one of the biggest debates in oil discussions. First, what is the difference? Regular mineral oil is a combination of different hydrocarbon blends, with different rates of evaporation and breakdown rates. As soon as your engine heats up, the oil characteristics start to change. Because of this, the manufactures have to load up with additives to try to stabilize the viscosity and acidity.  By the time you are due for an oil change, it is  quite different molecularly than what you put in there. In contrast, synthetics have a single molecule size, which means they are much more stable and resist breakdown and acidification.Machinery Lubrication Magazine has the best article on this that I have seen, called “Advantages of Synthetic Base Oils”. Well worth reading. If you are interested in high-performance additives, check out this article:

Also, it goes without saying, but proper filters are as essential as proper oil. Clogged filters are a sure path to destruction.

What issues have you seen with improper oil choices? Let us know! Also be sure to sign up for a free subscription to .  And please share this article with others who would appreciate it.

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