Bror Jace said:"I have been doing the oil changes every 12,000. I was thinking of only doing the oil filter changes at 12,000 and changing the oil every 24,000."
Think you'll save money doing this? How much ... $20-30 per year? That's foolish economy ... like the current F1 rules mandating 1 set of tires for racing and qualifying.
Seems a foolish gamble to me. I wouldn't go over 8,000 miles on an oil and filter without testing along the way ... even using Mobil 1's newest "15,000 mile" oil. I can't imagine changing my oil at least twice each year ... no matter what a pain it is.
WildBoar, you mean you run your car until it quits?
An Excel spreadsheet is a LOT easier.
Simply put your miles travelled in column A. On the same row, put your gallons consumed in column B. In column C, you'll write a formula:
This will automtically divide the miles by gallons and show an answer. I suggest you format the cel to round to the nearest tenth. Numbers out to 4-5+ decimals suggest a precision you're not getting with this method of measuring.
Repeat this using the next rows for each tankful of gas.
That's km not miles so it's not by any means a "foolish gamble". There are
many test results online of doing oil changes with synthetics at much higher
milege like 40,000 km with oil filter changes and top-ups.