Hammer Time: What's In Your Oil?

Steven Lang
by Steven Lang

Two hundred thousand miles.

It’s a beautiful moment for many a car owner.

As for me? Well, I admit that I cheated when I saw that number flash by in my wife’s car back in March. Like many an enthusiast, I had bought it used and was planning on keeping her daily driver for the long haul.

The question for me was, “How long would the long haul be?” Since I buy, fix and sell a lot of vehicles, and have deeply imbibed the fluids of wisdom at the Bob Is The Oil Guy web site, I decided to live my life on the wild side.

I performed an oil analysis.

What I got back was a smorgasbord of technical information, and one pithy summation that went like this.

“STEVE – 200,000 miles? Please! This engine’s still a spring chicken. Metals look great here, so assuming she’s still running well and you’re not having any problems, then there is nothing about this sample that seems troublesome at all. Averages are based on about 7,600 miles on the oil. You could run your oil a bit longer, for sure. The TBN is kind of getting low (it’s down to 1.4 and 1.0 or less is low), but the TBN tends to drop more slowly the more use an oil sees, so it might hang on at this level for a while. The viscosity was fine assuming you used a 5W/20. Try 9k miles.”

I loved the spring chicken part. Boy that made my day. However that whole TBN remark threw me for a loop.

And what in the heck was a TBN in the first place? The BAD number???

Well, that’s when my quest for knowledge became a great big time suck. I went here, and later here. It was that second “here” which truly opened my eyes to what that TBN comment actually meant, and why I probably don’t want to delve any deeper into the inner workings of motor oil.

My engine was great. Case closed. Barring any unusual events, I was good to go for many more miles. I could extend my oil interval to 9,000 miles from 6,000 miles with a synthetic blend. Or maybe I could do a full 15k with a high performance full-synthetic engineered for longevity.

Mobil 1 EP? Amsoil? Deep Purple? Sorry.

The sad fact is that my wife drives a common-as-kudzu Prius with a light foot, and enough driving distance for the engine to always warm up. The local shop charges $20 for a synthetic blend and a quality filter. My net savings would be maybe $5 if I did it myself once a year with synthetic (her car holds a little less than 4 quarts.)

I spent $25 to figure all this out. So much ado about nothing. It was time to take the thermometer out of the motor oil, and worry about one less thing in my life.

My technical results are highlighted here. In the world where enthusiasts have to deal with the economics of keeping a car for a long time, an oil analysis can help you answer the uncertainties of a valvetrain’s health. But chances are, if your oil is regularly changed and you use products that are API-certified, there are better ways to spend your money.

If your car quits, chances are it won’t be your oil’s fault.

Steven Lang
Steven Lang

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  • SCE to AUX SCE to AUX on Apr 30, 2014

    I've only seen two engines internally ruined: 1. My friend's Dodge Intrepid 2.7, which spun a bearing at 70k miles. No surprise there. 2. My other friend's 95 (?) Buick 3.8, which spun a bearing when the plastic timing gear teeth sheared off, traveled to the oil pan, and he restarted the engine after repairing it without cleaning out the pan. This car had about 80k miles. Better oil wouldn't have saved them, but better engineering might have.

  • Terrence79 Terrence79 on Mar 31, 2017

    Great write-up. I'm using the Amsoil 5w-30 alongside the nano-based Everglide EGS and I'm pretty impressed with this combination. I'm happy using Amsoil alone before, but my mpg has increased when I started using Everglide. It made my driving smoother and quieter too. Oil is indeed a huge factor in the longevity of your car.

  • 28-Cars-Later Seville - LS400Bhp 295 250Ft-tq 280 260Reliable No Yes
  • 28-Cars-Later No, and none of you should be either.
  • Arthur Dailey No.
  • Arthur Dailey My father had multiple Northstar equipped vehicles. He got one of the first Northstar equipped STS's in Canada and continually drove STS's on one year leases for nearly a decade. One of them did 'crap out' on him. It went into 'limp' mode and he drove it to the nearest GM dealer. The vehicle was about half way through its lease, and he was in cottage country (Muskoka). GM arranged to have it flatbedded back to Toronto. He rented a vehicle, drove it home and then took delivery of a new STS within about 4 days. There were no negotiations regarding repairs, etc. The vehicle was simply replaced. Overall he was pleased with the performance of these vehicles and their engines. We also found them a pleasant environment to be in, with more than enough power.
  • Bd2 If they let me and the boyz roll around naked in their dealership I'll buy a Chinese car.