[Bob.W]

Hello Learned Korean Car Drivers,

Just curious - we don't drive a lot of mileage (about 15k/pa, rural 25km runs for 80% of it) - but I've gotten in the habit of changing our PD's oil every 5,000km.

I always use the spec'd oil generally C3 grade, Valvoline & Nulon were the last few I used.

I used to do the oil filter at 5k as well - but decided it could do the full 15k or12mth interval instead.

With high grade modern synthetics oils (as C3's are) and non-extreme driving conditions, for the pretty benign D4FB diesel engine how do folks feel about this practice?

While I know its doing no harm (other than to my wallet and environment) - is it likely to be doing any good or would the $$$ and effort be better spent on other areas?

Much thanks for your thoughts
Bob

[CraigB]

It'll be fine doing it once a year, twice a year if you were doing a lot towing or other severe treatment.

Three times a year is quite excessive without changing the filter between oil changes you were only wasting the oil anyway as it's instantly contaminated via the old filter

[Bob.W]

without changing the filter between oil changes you were only wasting the oil anyway as it's instantly contaminated via the old filter

Thanks for your reply & thoughts.

Just curious, how do you feel that 'new' oil would be contaminated (which is very subjective so I'll assume this is meant as being to a significant level) by the old filter being still in place?

Pressurised system, contaiminants above a certain size are trapped in the filter, yes a very small amount of old 'dirty' oil in filter - but not sure how significant contamination takes place?  :-)

[CraigB]

There would be enough old oil within the filter to start degrading the new oil at an accelerated rate, particle blockage isn't so much of a concern but more the early breakdown of the oils structure.

[Bob.W]

There would be enough old oil within the filter to start degrading the new oil at an accelerated rate

I have never heard of old oil 'catalysing' new oil degradation - tried  to find info on it but coudn't - do you have any links on it? 

[CraigB]

I have never heard of old oil 'catalysing' new oil degradation - tried  to find info on it but coudn't - do you have any links on it?

No links, just years of knowledge through the racing industry