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Discussion Starter · #1 · (Edited)
The internal combustion engine is not particularly efficient. Typically a gas powered engine is about ~60% efficient and a diesel is ~85%. The higher the compression ratio, better efficiency, so a gas engine at 10:1 compression ratio is less efficient than a diesel at 20:1 CR. Plus of course diesel fuel produces a bigger bang for the buck.
So if 60% of the combustion ends up producing power (HP), the rest is lost to heat escaping, (exhaust), and mechanical friction losses. Which leads us to today's topic, Engine oils.
If you buy a jug of oil, on the back in a little circle, you will see something like"SAE 5W20, API SN, GL-5"
What's all that mean? SAE (The Society of Automotive Engineers) certifies the oil's viscosity as 5W20. What is viscosity? Viscosity is a liquid's resistence to pouring. Water has a viscosity of 1 and is the benchmark. So 5W20 starts out as 5 and slowly gains resistence as it warms up until it is a "20 weight."
Hydrocarbon or crude oil based, "Dino" oils must have additives to alter the viscosity, whereas Synthetic oils are formulated to react to heat in a stable transition from start to fully heated. Dino oils have irregular molecules that break down over time, while synthetic oils have virtually identical molecules that remain stable and pourable from as low as -50 F to +400 F. Both types get "dirty" over time and need to be changed. Don't use diesel specific oil in gas engines. Diesel oils have more detergents and diesel additives.
The API or American Petroleum Institute monitors the manufacturers requirements for oil's wear properties, additives etc. and issues ratings. Gas engine oils started out at SA and are now at SN. GL-5 is a European rating similar to the API and is often referenced for German vehicles. Diesel is listed as a C rating, up to CJ currently.
One has to be careful when purchasing "Synthetic" oils. There is no such thing as a fully synthetic oil (marketing name), since most synthetics have a maximum of ~30% base stock. A company can call an oil synthetic as long as it has been a chemically modified petroleum base stock. If you look at the MSDS for a particular oil and it lists Hydrocarbons, Parafins, or modified petroleum as the base stock it is not, to my mind "true" synthetic oil.
A number of years ago Mobil 1 sued Castrol over that exact point but lost when Castrol proved that their base stock was sufficiently modified to qualify as synthetic. The chief advantage of synthetic lubricants is pourability when cold, which protects your engine on start up and improves fuel economy during warm up..
In my opinion a "true" synthetic should have a base stock of something like Ester oils, Poly Alpha Olifins, plus other additives, including zinc compounds. There are many types of synthetics on the market, some are even purple or red. The colour has no bearing on the formula. All the major refiners are producing good synthetic lubricants.
My personal first choice is Exxon's Mobil 1. I don't agree with their former tanker captain hiring practices, but they make a good product, since 1973, and stand behind their lubricants
So buy the correct viscosity for your vehicle, use a quality filter, and change as required.
As always, your questions, comments, and likes are welcome.


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Time of an oil change this weekend. It's been almost a year but during this time <1,000 miles. I sure hate changing oil with so little mileage but I am concerned about condensation since the car sits a lot with mostly short trips.
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I think it's also worth discussing oil life, oil contents, and reports. Factoring out special situations, racing, offroad, exclusive very short drives, etc, oil can last a long time. Over the past couple of years I have starting exploring this with our Fusion. It's also saved me a motor in my Bullitt.

I send a sample off to BlackStone Labs and they report back things like metal content, chemicals, and viscosity. I first tried around 6,500 miles. They suggest going longer. At 8,500 miles they suggested again that things were excellent and go try for 10k or more. Just changed it at 1yr and 9,300 miles. I expect another good report. Oil used is factory fill Motorcraft blend.

The Bullitt was running perfect but the oil report shows VERY high metal content. It continued to raise to the point of major concern. I then began an investigation and found the timing chain guides wore through. I would have never known until real damage was done, as there was no noticeable noises. A few more months from now, I will change the oil and see where we are. Hoping for good things. For the B, I change about every 4k as I drive short trips, track it, and like to change around once a year. It gets way dirtier than the Fusion, probably because of those facts and the K&N filter.

Needless to say I am a HUGE fan of oil reports now and will be doing it with all my cars. Maybe not every oil change, as it's $28, but perhaps every other change depending on situation.

Looking back through my teenage years and early adult years, I can't imagine how much money I wasted on 3k mile changes. Marketing won me over and I believed them just like most of america.

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My BULLITT is typically driven no more than 4 to 5 thousand miles per year.

I change the oil once a year, Full Synthetic 5W30 and I use an extended life synthetic oil filter, usually pay $15 to $20 for the filter alone.

Change it every year the day before it goes into heated winter storage end of October.

I only put 5,000 kilometers or approximately 3,000 miles per year on my 08 F-150. 5W20 Full Synthetic with same quality filter as BULLITT. When I change it once a year, it's still clear.

Even my 2017 Mazda CX3 gets Synthetic Oil at the Mazda Dealer every 8,000 kilometers (5,000 miles).

No need for an engine block heater in the winter with synthetic.
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