Oil Change Interval (OCI): Are the Dealerships Ruining Your Engine? – Part 1
UPDATE: This is part 1 of a 2 part series. Click here to go to part 2 where I show the results of my 10k OCI with an APR Stage 1 93 Octane tune!
Back in the, not so distant, day it was common knowledge that cars should have their oil changed every 5k miles or so. With the advent of fully synthetic oils and manufacturers offering warranties that cover the first few oil changes, things have changed. Now when you open up you car’s manual the interval at which they suggest changing the oil has, in most cases, doubled to 10k miles!
Is this new recommendation a result of advances in technology which cause less stress in the engines? Advances in oil which prolong their life? Or just a way for the dealers to get away with not having to pay as much for the oil changes they have so graciously offered to pay for?
I just purchased my first car, a brand new 2010 Volkswagen GTI MKVI. Before now, I knew NOTHING about cars. I didn’t have to since I didn’t own one! Now that I have such a marvelous piece of machinery, however, I am trying to learn as much as I can so I can better maintain my car. As my odometer quickly reached the 5k point I set off in search of an answer as to when you should really change your oil. What I found was a divide between the drivers of the world. On the one hand you have those drivers which swear by the old mantra that you’d be a fool not to change your oil every 5k miles. On the other you have those drivers that believe in the longevity of fully synthetic oils and believe that they can last well over 10k miles (BMW suggests changing your oil every 12k miles!). Neither side had proof that their argument was correct. It was all anecdotal evidence.
Fortunately, there is a company by the name of Blackstone Laboratories that analyzes your oil and provides an estimate of how much life your oil has left. This life expectancy indicator is known as Total Base Number (TBN). I am by no means an an expert on this subject so I will refer you to Blackstone’s page where they explain in detail what TBN means.
Both I and a fellow GolfMK6.com forum member by the name of Frank (aka FN in MT) have sent in samples of our oil to be analyzed. With the analysis we are hoping to find out how much longer we could have prolonged the oil change without any harmful effects.
The following is Frank’s short run down of how he broke in his engine and what type of driving he did in the 5k miles before his oil change:
2010 GTI, 6 speed manual.
Purchased 2/20/2010
I didn’t approach redline for the first 600 miles, shifting at no more than 4500 rpm. Made fairly easy by my snow covered roads the first two weeks of ownership.
As my roads cleared up I started to exercise the car by shifting nearer to redline, and running it more aggresively through gear changes. By 2K miles I’d already made a few blasts through the gears and held it at 120 mph for several miles. I closely monitored my coolant and oil each evening. I never noticed any drop in coolant or engine oil levels.
At 2500 miles I made a 2400 mile trip from MT down to New Mexico. Most of the trip was fairly hi speed Interstate, but I also travelled some 2 lane 55-65 mph highway through UT and AZ. As well as visiting a few of the Parks. My driving was “spiritied” but within the Law.
Our fairly deserted highways are one of the perks of living in Montana. Allowing me to safely run up to triple digit speeds for break in…but not encountering another vehicle while doing it.
At the 3K mark I noticed the engine revving easier and now at 5K it’s surely revving faster than when new. My mileage has gone up as well. I can get 33 mpg on the highway at 75 mph. More “spiritied” driving on 2 lane roads with up and downshifting for slower stretches or to pass slower vehicles I’m averaging 26 to 28 mpg.
The following is the report that Blackstone Laboratories sent him. One thing to note is the TBN of 4.3. While we don’t know what the baseline TBN of a virgin sample of the same oil is, we can assume that on average it should be around 12. As stated in Blackstone’s site, “When you first start using the oil the TBN tends to drop sharply. Then it levels out and drops more slowly after that. A low TBN test result, meaning very little additive is left, is down around 1.0 or lower.”
*Clicking on the image will take you to a higher def .png version.
How much longer Frank could have waited for an oil change is not specified by Blackstone Labs in this report, however, in mine it is.
I ran my car a little different than Frank. I pushed it VERY hard. Not only did I not wait the suggested mileage before I started ripping into the car, but I also took it to the track and drag raced at full throttle within the first couple thousand miles of having the car. Also, I waited a little longer (approximately 1.7k miles longer) for an oil change. With that said, here is my oil analysis report:
*Clicking on the image will take you to a higher def .png version.
As you can see in the comments section, Blackstone Labs states that the TBN of my oil was 4.1 and suggested that I could run it up to 8k miles before changing it. I am pretty sure this is a conservative number (they don’t want to get in trouble) and that I could have indeed ran it for the suggested 10k miles without a problem.
From this I can conclude that if my car had a TBN of 4.1 and according to Blackstone Labs I could have gone until 8k miles before an oil change, I am pretty sure the average driver should have no problem changing the oil every 10k miles.
So where does that leave us in this debate of 5k or 10k oil change intervals? Every engine is different and every driver drives their car differently so when you should change your oil ultimately depends on what you drive and how you drive it. I, personally, will be changing the oil every 10k miles from now on, especially since the engine break in is over which is what causes the harshest wear on the engine. In my particular case, it seems as if the manufacturer is indeed correct in it’s recommended oil change interval and as such I will be adhering to it.
UPDATE: I have reached the 10k mile OCI mark and have sent my oil in for analysis. Click here to go to part 2 and see the results.
2 Responses to “Oil Change Interval (OCI): Are the Dealerships Ruining Your Engine? – Part 1”
August 27th, 2010 saat: 3:34 pm
The question should really be – How much of that iron is continuing to circulate in my engine? The size of the particles is of paramount importance in deciding how often to change your oil. If they are smaller than the pore size of the filter that is fitted then they are just flowing unabated throughout you engine regardless of how often you change your oil.
The only way to remove the iron particles effectively is to fit a magnetic device somewhere in the oil loop. This should be done from new as it will remove the wear in particles that start the wear out of the engine.
September 7th, 2010 saat: 12:44 pm
Great article. It’s great to question the status quo and in your case you got the answer. As a former quick lube operator I can tell you that consumers have been swayed to follow the conventional rule of thumb which is every 3000mi/5000km regardless of manufacturer recommendation. In reality, oils today are designed to perform many functions: lubricate moving parts, suspend particles, improve fuel economy, reduce emissions and improve overall engine efficiency. Couple this with the fact that todays engines are designed to run cooler and more efficient means less frequent servicing. In the lube industry we are seeing a shift towards longer oil change intervals and consumers following manufacturer recommendations. Less frequent oil changes also results in lowering the amount of waste oil produced by vehicles. One thing to bear in mind is to also invest in a better oil filter when doing extended drain intervals.
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