Most optimal oil change intervals

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barrylarry, Mar 27, 8:26am
i get various answers from people on this. And I dont really think theres an "exact" number to it. But I just wanted to see what most of you think. I know some people who change oil every 5000 k's but to me thats just a waste of good oil imo. I wanted to see what the experts on here can share. Personally, I change my oil every 15k on my current carburetted car. I used to change every 25k on my past car which had an EFI. But i noticed the oil gets darker fast on a carby, due to less cleaner burn perhaps.

gunhand, Mar 27, 8:29am
I'm an oil waster. every 5000kms. Oil is cheap as and is the life blood of any motor. that takes oil.

a.woodrow, Mar 27, 8:32am
too many variables. Depends on type of engine, usage and what oil you are using. Old diesels engines (and some old petrol) every 5k is good. 90's jappas usually good for 10k, 15k if you are using good oil. Many new vehicles service intervals are creeping up on 30k, that's stretching the limits of oil tech though

clark20, Mar 27, 8:34am
My V8 Commodore does 15000km, but needs 8.4L oil to do so. Capacity is the key here. Do whatever the manufacturers says.

bwg11, Mar 27, 8:36am
What he says ^^^^ Oil is cheap. Service intervals have become competitive between manufactures who don't care if potential engine life is 300k or 500k.

a.woodrow, Mar 27, 8:40am
Without knowing what car you have and what oil you use, I would say you need to change your oil nearly twice as often as you are now!

stevel_knievel, Mar 27, 8:41am
6 monthly.

franc123, Mar 27, 9:13am
TOO competitive, its only done because it appears to be environmentally friendly and because its what buyers (or more likely their accountants) want to see. These whizzbang lightweight high speed Euro diesels that are often more Bang than whizz MUST be suffering more wear under local conditions with these inappropriate service intervals, not only with the engine internals but with the emission control systems too.

socram, Mar 27, 9:42am
Service on one of mine is supposed to be 20,000kms, but as usage is low, it gets the service more often. A lot depends on the type of usage. I have a rule that if I can't run it for enough time to warm up the oil, then I don't use it.
Stop start motoring means the oil needs changing more often than a load of long journeys. If it looks black - oil change is overdue!

mugenb20b, Mar 27, 10:02am
My old turbo diesel Hiace (1kz motor) gets its oil and filter changed every 5000kms or 6 months. V6 Hyundai gets one every 7500kms or 6 months and my crappy carburetted Corolla gets one every 6 months regardless of the mileage which is usually around 2000km mark. The Hiace and Hyundai get long hot runs all the time and the 'rolla does a lot of short cold trips.

kazbanz, Mar 27, 5:37pm
There is no definitive answer for this question.
If you use milage as the timeline then
The reason for this is that everybody uses their car in a slightly different way and the vehicle itself will contaminate the oil in a different way.
The guy in a modern petrol car driving 80km per day will need less oil changes than the little old lady in an older car travelling to the shops and bingo once a week.
but then if you use time rather than milage then argueably they should be changed at the same interval roughly
My instructions to my older customers is to change the oil with every WOF.

stevo2, Mar 27, 5:56pm
Both my petrol cars are 10,000km or 12 months (whichever occurs first) and my Hyundai diesel van is 15,000km or 12 months, as per the service manual.
None of them require a top up between services.

brapbrap8, Mar 27, 6:01pm
My local dealership recommended at the last service I get the oil changed every 20,000km rather than 15,000km in my ute because I virtually only ever use it for longer trips, mostly highway mileage. That works out as a roughly every 6 months.
Not sure if I want to extend it out or not, not sure how long I will keep this one for.

joanie32, Mar 27, 6:14pm
I sent oil from our family car away for analysis, as we send oil every couple of days at work. 20k since last oil change and it was as new, so tested again @ 30K Still fine. I think people get way too anal personally, oil doesn't wear out, it only becomes contaminated. If conditions are good I see nothing wrong with 20K.

mugenb20b, Mar 27, 6:32pm
True, but all the additives get used up. Besides, as mentioned above, oil and filters are cheap.

tamarillo, Mar 27, 6:49pm
I couldn't do 15, it's too cheap an insurance and too good to miss. 10 is as much. Someone pointed out on a car being tested that the servicing intervals had grown yet the engine was unchanged. They did it to match competitors. Stuff that.

gazzat22, Mar 27, 11:02pm
Change the filter at 6 months,oil and filter at 1 year,
.

joanie32, Mar 28, 2:53am
I dont buy cheap, and do it less.

gazzat22, Mar 28, 3:42am
Oil doesnt break down,it just gets contaminated with the byproducts of combustion viz water,carbon and petrol etc. oil can be filtered and re-refined and used to be at a refinery in Te papapa.it was sold cheaper than new oil but i think the oil companies worked to close it down 20 odd years ago it was decided it was better and easier to change the filter more regularly than the oil and cheaper.i worked with a guy who had a toilet roll filter fitted to his vehicle a triple stacker ie 3 toilet rolls which he changed at 1000miles .The oil was as clean as a whistle after 60,000 miles but i guess the oil companies bought the man who made them out and they dissappeared from the market.no bulls t

mugenb20b, Mar 28, 4:24am
I didn't mean cheap as in quality. Oil in general is cheap regardless of the price.

bwg11, Mar 28, 4:29am
Yes, back in the 1960's re-refining was quite big, the name Glydol comes to mind. In those days some people preferred to use a "straight" mineral oil (no additives). Back then family cars produced about 40 bhp/litre, and the demands on lubricants were quite moderate. Today, with family cars approaching 100 bhp/litre, oils really need their additives to provide adequate lubrication. These additives do get "used" or worn out. Just keeping the oil filtered and "clean" is not enough, the additives must be replenished.

ema1, Mar 28, 9:00am
My sentiment too, all my cars over the years have had the 5,000km treatment religiously and for the exact same reason as you gun.
Has paid off handsomely for me with comparatively trouble motoring over the last 48 years of car ownership.

joanie04, Mar 28, 10:35am
Every 10,000km or 6 months, which ever is first, as instructed by my father a mechanic and my brother also a mechanic. Usually 6 monthly. Oil and oil filter each time. Tends to use a little bit after about six months. The other half asked me the other day how often a car needs to be serviced as the service light came on in his. After him owning a diesel van for years and me constantly telling him how often it needed to be done and being ignored I was surprised he had to ask.

gammelvind, Mar 28, 6:32pm
My own car oil (synthetic) and filter every 10,000 km. Work van every 15,000 now, then again I do 1200 km a week so 15K doesn't take long to achieve and is all hot running.

pdc1, Mar 28, 9:05pm
My own risk started in the early 90??