People don’t often think about what their oil can do for their gas mileage. The two are seemingly unrelated, and if they are mentioned they are mentioned in an off hand manor that doesn’t add up to much, just fine tuning your mileage. I have data that says differently though. This graph is a graph of the last couple of months the gas mileage I have been getting in my 1999 Toyota Corolla.
Being that it is an automatic getting 10mpg over what the EPA rating is said to be is pretty good. But I’ve been wanting to push that number over 40mpg for a while now, I started to give up after three hard attempts at better mileage and one base line run (the first two were attempts at over 40mpg the third red bar is a base line using A/C, and driving hard, the next was yet another attempt at over 40mpg) the next runs I did were just me driving normally, nothing impressive and slowly going down hill on the graph. That is until the last bar with 39.61mpg even with normal driving (no attempt at great gas mileage, A/C usage, hard cornering and launching the car much faster than the three 38mpg runs) was shortly after an oil change. Because of an oil leak I’ve been forced to run thicker oil in my car (10W-40) and even added a thickening agent to the oil to stop the leak. This slowed the oil leak to a point that I only would lose two quarts of oil between oil changes (I’d replenish one quart and then by the time I was ready to change the oil again it would have lost another). needless to say it’s a pretty bad oil leak, and I didn’t have the money to fix said oil leak as it requires that I pull the head and rebuild it. I can’t afford even a day of down time so I must purchase a new head, and get it ready so I can do a quick swap. That’s beside the point right now though. I replaced a few of the seals around the head that I could get to without pulling it, and the oil pan seal in hopes of stopping the leak. At the same time I decided to run better oil, and definitely wanted to change the filter after watching some youtube videos on the construction of oil various oil filters I decided to go with K&N oil filters as they are the same price as the Fram filters I have been running with but unlike Fram they actually use quality materials not a paper filter, and crappy under sized drain back valve like the Fram does. I figure between the synthetic filter media in the K&N filter and now running 5W-20 synthetic oil the gas mileage has just increased that much since the motor doesn’t have to work as hard to move the oil around, or force it through a restrictive filter.
