Quote:
Originally Posted by radioranger
lucky you checked the oil, the tcw might have saved you some wear there, I've noticed and it was actually used in WW 2 that if your oil level is low you will get more power, this due to foaming or the crank hitting the oil in the pan, Many times you'll here stories about how a car was running better than ever , just until the oil light came on and it broke down
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I've noticed an increase in FE many times with lower engine oil levels. If I'm getting unusually-high FE readings, it's time to check the oil...
Quote:
Originally Posted by radioranger
MY truck does seem to ping more on hills so next tank bought some high test and it fixed that with a few gallons of it, back to regular fuel now and my feeling is it is a good idea to run the tcw once in a while
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Interesting notation with pinging. Ardent mentioned the same problem with his truck (higher FE, but ping under load)...
Quote:
Originally Posted by Ardent
I also puzzled over how this could be helping mileage. ... I think I found the answer though when I towed a heavy load with my pickup. When merging onto the highway with that heavy load on an moderate uphill grade, the engine experienced some severe preignition ping/knock that I had never heard before. Retarding the timing by 2 degrees in the high load areas fixed that problem.
I believe that the mileage increase is because of the octane reduction caused by adding oil to gasoline. An engine with safe/conservative ignition timing then benefits from the timing "advance" caused by the added oil. I expect that I could see the same mileage increase by more optimally dialing in the timing.
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I run premium/91-Octane fuel, due to some modifications (hotter thermostat, Warm Air Intake, full mechanical advance on the distro, and a full radiator block in Winter). I notice pinging whenever I use 87 or 89 in the Summer, and 87 in the Winter. The solution was to run higher octane all the time. The combined effect of better FE has outweighed a slightly higher cost per tank. So, I'm keeping an ear on it, in case the oil does lower the octane rating.
Regarding the oil selection -- I used to exclusively use Castrol engine oil until about a year or so ago. I noticed one day that it was a BP brand, which I stopped using after the Gulf mess. Add to that an existing Exxon/Mobil avoidance and the options were thinning out. I tried Valvoline "Next Gen" recycled oil when it was on sale and found it to do the job. With a leaky cam bearing seal, I have been trying different products and viscosities (with a focus on that FE-Longevity line of balance). It may be beyond "conditioning" with additives, but we'll see...
-RH77