Which is more important, time or mileage?

[brianl703]

I last changed the oil in my mom's car in August with Motorcraft 5W30. I just changed it again today with Havoline 5W30. In that time span (a little under 5 months) the car was driven about 1800 miles. Most trips are under 10 miles.

In this situation, which is more important--time or mileage? Going by the manual, I should change it every 3 months. Going by mileage with a 3000 mile OCI, I'd be changing it every 8 months or so.

I'd like to keep this car in good condition--it's not a lease and so the long-term effects of whatever I do are important. Given that, what should I do?

It's a 2.2L Ecotec, by the way.

 

[Bryanccfshr]

Change it every 6 months and it will be fine.

 

[Auto-Union]

All I can say is I do 100% of my services (quite a few cars) on TIME intervals. 2-3-4 times a year. Pick an oil that suits the conditions and APPROXIMATE miles encountered in that time.

 

[Gene K]

1. Synthetic and change it once a year (warranty allowing).

2. Dino and change it every 6 month.

 

[Cutehumor]

another vote for change dino every 6 months.

 

[Patman]

My mom only drives about 3-4k per year and most of it is short trips, and I ran her last OCI to almost 2 years! She put 7600 miles on the oil in this time. She's got a 2001 VW Golf (2.0 engine) and I'm running GC in it. The UOA came back looking great, low wear metals, strong TBN still, and no moisture in the oil.

The way I see it, with such low mileage anyhow, even if the wear metals were somewhat high, the engine would still probably last another 100,000 miles, so we would effectively never see the end of this engine's life, so why bother doing so many oil changes on it?

 

[johnd]

There is another factor to be considered. A car that isn't being driven isn't deteriorating the oil. Other than that the best senario is a car that stays running all the time like a taxi. The worst case is a car that gets lots and lots of starts and really short run periods, especially in cold weather. There are two many variables to jump to conclusions. I bought a car in 1980 that hadn't had the oil changed in three years and it looked like new oil because it pretty much hadn't been driven in three years, the person that owned it had gotten two old to drive.

 

[tsmay51]

I vote conventional oil on 5k oil changes or one year. Whichever comes first.

 

[Vaca]

You may want to consider a third factor when you choose an oil change interval - the length of each trip.

If, for instance, the car is driven on a few long trips throughout the year, then maybe a once a year on dino would be fine. If, on the other hand, the car sees lots of short trips which would allow water and such to build up, then you'd likely want to change it more often, maybe every 6 months.

Whether the car sees fewer long trips or more frequent short trips, I'd use "regular" oil. At the rate of mileage accumulation on the car, it'd be hard to appreciate the benefits of a premium synthetic. The rest of the car will be worn out well before the engine.

 

[Oil Changer]

UOA proves different but the oil companies would like us to believe that time and distance are equally as important. For as long as I have been alive I have heard, "3000 miles or 6 months, whichever comes first...".

 

[Ferndog]

In my opinion, the months and/or miles are simply reminders to the general public. In addition to helping maintian the engine, oil change intervals are typically a trigger for other maintenance like checking other fluids, servicing tires, checking lights, etc.

I would argue that the driving conditions weighed against the oil are the true indicators. But the general public may not understand driving conditions, oil quality or UOA and thus use the months/miles reminder. The goal is to find the weakest link.

For example, used race oil after a NASCAR CUP race may show the oil in perfect condition but one pass in a Top Fuel Dragster may dump 4 to 10% fuel into the oil. Similarly, a taxi driving 23 hours a day may actually be very kind to engine oil while a car driven one mile every weekend may generate large amounts of low temperature sludge. It all depends.

You also have to know what to interpret from the UOA. For example, the zinc antiwear additive may show a consistent ppm value in an xray test thoughout the life of the oil even though the activeness of the additive is slowly depleting. Similary, will the UOA tell the amount of anti-oxidant left or just tell you once insolubles start to accumulate.

 

[RD400]

Quote:

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"3000 miles or 6 months, whichever comes first...".

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So if 3000 miles is a farce with modern oils, then 6 months probably is too.

 

[mitchcoyote]

In your situation time is most important. Change every 6 months....

 

[Big Jim]

The time issue is less ctritical than it was in years past. First of all, the oils are better, much better. Second, the engines are built better, both in design and materials. Third, there is very little fuel dilution during warm up on fuel injected engines compared to carburated engines.

When fuel dilution was heavy, the acidic products created were #@$%! on bearings and rough on other parts as well.

Under today's conditions I'm sure that you would be fine doing a twice a year oil change. If you really want to know for sure, get an oil analysis, one that includes TBN.

 

[Gene K]

Quote:

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In your situation time is most important. Change every 6 months....

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Mitch are you feeling all right? Should we call a doctor?
No mention of the Devil's own brew (5W-20) at all?

 

[brianl703]

Thanks. I think I will just change it every 5 to 6 months. While the car may be used for short trips now, there is always the possibility that it will be used differently in the future.

 

[Auto-Union]

To further explain how imo time is a better "trigger", basicly ignoring miles-
In a certian time, a car that accrues less/low miles ~likely~ takes shorter trips and is actually ready for an OC after a thousand 3-mile trips in however many months. Another driver who accrues twice or even three times the miles in the same few months does not really need an OC at 3000 miles because they are taking ~longer~ trips? Does this sound right?

Can the long tripper OC at 6000 or 9000 miles? Yes, we know that. Does the short-tipper need OC at lower miles? Yes, I've said how my soccer-mom cousin's GM OLM would go off at 3500 miles. Ok then, what normalizes OCI for both the short tripper and long tripper? Time.
I also like time intervals because it's more convenient in general and takes the guesswork and OCD out of counting down miles-based OCs. 6 months, boom. 4 months...whatever is appropriate. People who do not even drive their cars a few hundered miles a year because they sit long periods can do Time OCIs too. FTR- I am doing 4 synthetic changes a year, approx 7500-8000 miles a pop. I was not comfortable with 4 months/10k ocis. I hope this helps, I think it's good advice for non-BitOGers....TIME inervals.