My Thoughts On Oil change Intervals

Created 12/7/2010


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Introduction

I maintain 24 vehicles.
My Cylinder Index is 85.
Some are automobiles and vans that are used on a regular basis and some are vehicles or machines that are used seasonally. Most of the "seasonal" vehicles get an annual oil change, unless they are "parked" all season.
The two vehicles that we drive almost every day get an oil change every 25,000 to 30,000 miles. And that's what this article is all about.
One of those vehicles, a 1992 Nissan Sentra has 335,000 miles on it and the other is a 1993 Plymouth Voyager Minivan with 248,000 miles to its credit. We have bought, operated and sold several other vehicles and they have been treated the same way. The youngest that any one was sold was at the 135,000 mile point with oil consumption never worse that about 2500 miles per quart.
We have never had the head(s) or the oil pan off of any of them.

We All Change Oil Too Often

I feel that the 3000 mile oil change idea came straight from the marketing department of companies that sell and make engine oil. This was supported by the auto companies, partly because its "no skin off their teeth" if you change oil too often.
***** AND, I think--- The car companies have found, especially in these days of the "Rapid Oil Change" store, that it is easier to get an "average" customer to change oil than to check it and add a quart as needed. This, in the days of self service gas stations. (In the "old" days, a guy would come out to pump your gas, clean your windshield and check your oil!!!) Not so any more, is it? You have to take the initiative on your own. Ask a dozen non-motor heads how often they REALLY check their oil
See, Here's how I think they auto companies reason it out:
They don't want their cars to fail from lack of oil.
They realize that the value of a good used car helps the sale of their new ones.
So, they can't have their car engines binding up just because the owner doesn't check the oil often enough.
Okay, so they figure that a car's crankcase can get at least a quart low, and even 2 quarts low, maybe, without damaging the engine.
Here's the kicker:
If they can convince the customer to change the oil at 3000 miles or so, then the chance that even a pretty well used engine is going to fail for lack of oil is pretty low. So That's what they do.

Now, I need to tell you that I always use synthetic oil and I change filter with each oil change.

The Green/Green statistics:

8 oil changes, in a car that holds 4 quarts of oil plus one for the filter equals 8 X 5 or 40 quarts of oil.
1 oil change in a car that gets only 3000 miles per quart per 25,000 miles equals 1(oil change) X 8(quarts that you add every 3000 miles plus 5 (quarts for the oil and filter change) equals (8 X 1)+ 5 = 13 quarts.
A savings of 40-13 or 27 quarts of oil that don't have to go into the environment in one way or the other.
Why do I say "Green/Green? That's because there's less impact on the evironment and less cost in "greenbacks" to the auto owner.

In Closing:

If you doubt me, google around and you will find that most auto manufacturers have at least doubled the oil change recommendations for their cars within the last couple of years.