The owner's manual of S40 MY07 quotes only about mileage, none of the time interval with lower mileage.

The car is driven only 3 or 4 times a month, 50 miles each, 90% of highway.

People say oil will break down over time, suggesting it to be changed every 6 months or 1 year.

I agree with them, since they have more experience. But I wonder what breaks down and how fast they do.

There are companies specialized in oil analysis out there right? Tells you factors and conditions of the engine oil. But there is no company reachable to analyze engine oil in Korea.

Have you seen analyzed data close to my driving habits?
; Very low mileage, Very few times driving almost only on highway. Extended oil change interval.


Thanks a lot.

 

My understanding is that, while there is some breakdown, the primary reason for changing oil is accumulation of water and blowby acids in the oil.

From your profile, it sounds like you are running the engine long enough to dissipate the water.

I wouldn't extend the 6000 mile interval, but I also would not worry about waiting beyond the 6 month interval.

 

Thanks for the help mf70! It seems oil manufacturers also agree with you. They say its mostly upon engine running time, as marine engines. I'm gonna have it sit tight a bit longer.

 

The maintenance interval for a P1 S40 is 1 year or 7500 miles.

 

Thanks damien you're right. What the manufacturers told me is that for city driving or idling, Engine running time could reach the recommendation without km driven. They said thats why they put year interval.

 

Hi There Rob Here, I would suggest changing the eng oil 6 Monthly and the filter every alternate time. We do that for the diesels here in SA in severe hot weather but with low Kls.

 

Thanks Rob
Yeah, the often the better. It considerably low regard as the cost and love on thr vehicle itself

Do you feel the difference between 'cheap and bad' engine oils and ' good' ones? when they both get specifications such as SN.

 

That API service rating is a minimum. All the oils that carry it meet the minimum requirements for that rating. The reason oil with the same rating is more expensive is usually because it has a better base, better additives and is a better oil that affords more protection to the engine.

 

Thank you again for contribution
Yes, I agree with you. , Now, my additional question is : "Is it possible for an End-user without chemical analysis tool or equipment to determine 'good oil' from bad ones?"

Or there should be some tools I can afford of?

Unfortunately in my place there's no oil analyzing company..

 

Hi there. In my experience with all automotive oils is that if you buy cheap you get inferior product. I would make a call to the oil company and ask them which would be the best oil to use for your application. I don't believe that they would misdirect you.Cheers Rob

 

Oil like antifreeze doesn't break down. It does get dirty and can get diluted and the additive package can get used up or break down but not the oil itself. That's the reason it can be recycled, re-refined and then with fresh additives sold and be as good as virgin, first use oil. Valvoline sells "Next Gen" which is recycled oil.
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As for new "bad oil" I don't have a clue. Any oil that meets or exceeds the specification for an engine is good oil. It's like 80% lean hamburger. If 80% is good enough for your that's your minimum and some will taste better than others and have different prices but you can always get 90%, it's just a little better.

Oil API specifications get superseded every so often and in our 850s it's better to use the latest API spec oil available.

As for how often to change a low mileage car you'll get many different answers for many different reasons. The best one I can think of is condensation and combustion by products sitting in your oil pan. I do mine on my Supercoupe about every 4K (Yearly) since that is about a years miles. If it sat in the garage more and only did 1 or 2K yearly I'd still stick with yearly. Just easy to remember as I have a couple that don't get driven much.

This is the place to go (IMHO) if you want to know about oil. Bob Is The Oil Guy | The Internet's Number One Motor Oil Site