It's either 5w-30 Pennzoil Semi or 10-30 Toyota Semi oil for my Persona (2 1/2 years old / 70k KM). These two are fantastic engine oils. So much more smoother, more responsive and powerful / better torque engine due to less drag.

This post has been edited by jasondotcom: Apr 24 2012, 10:37 AM

8000km for NA is ok

When to change oil also depends on how big is your oil sump. Assuming everything the same, surely one with oil sump of 10 liters capacity will last twice as long as one with 5 liter capacity. That's why European car usually have bigger oil sump.

I'd agree with Optiplex330. Usually recommend my customers to change at longer intervals if they use like 6-7litres of engine oil

What is the oil sump capacity of common cars like Wira/Waja/Myvi/Vios/City?

4-5 liters or less.

notice how you only need 3.x liters of engine oil commonly?

that's why I am puzzled.
Why 3.xL already hit FULL mark at dipstick when oil sump is 4-5L ? Must it have some empty space to "breathe" ?

"or less"

also the dip stick typically doesn't measure the entire sump capacity and/or the engine components/oil pump etc.

Another way to extend OCI is to install By-Pass filter but then you have to monitor the quantity of additives left in oil. Too troublesome so easier to just change oil at specified interval.

any recommendation for engine 4g13, 60k mileage done so far.
last time i use shell hx7, quite good. now eneos 15w-40 since i know a dealer that provide delivery in front of my house. cant feel any different.

btw im not always drive my car, only weekends use. monthly mileage is not even 500km

if you're willing to spend, can try out liqui moly or torco. considering your mileage, you could opt for between 3-4 months OCI

not sure if the oil can last over 3 months though. as its mileage OR 3 months, and people who drive their cars daily rarely reach 3 months and change prior that due to mileage reached.

The theory is, once the oil poured out from container, they start to deteriorate regardless of whether you drive or not drive. Hence either 3 months or 5000-km etc.

IMO people are unnecessarily concerned about engine oil. As long as you use oil of the correct viscosity and grade and change at designated interval, your change of having engine oil related engine problem is as great as being hit by lightning. Meaning, extremely rare. And this is regardless of Mineral or Synthetic.

they're hydroscopic.
But I cant find the explanation to cars with 10,000 or 15,000.00 OCI on the service manual

Most likely having bigger oil sump or for those huge Euro truck, also By-Pass filters. Scania actually say you can use Mineral Oil for their truck for 120,000-km. So there goes the urban myth Mineral oil only good for 5000-km and FS 10,000-km.

That's where most people do not understand the workings of the engine and then wonder why they can't stretch the oil change intervals. It has nothing to do with the degrading of the engine oil but rather the contamination of the engine oil that shortens the oil change intervals. BMW tried their EURO standard 25k km oil change intervals here and ended with slugging issues and dead engines.

The oil itself will last a very long time if there are no contaminants. For example, gear oil works harder than normal engine oil but last much longer as there are no contaminants being introduced to the system. With every combustion of the engine, blow-bys leak past the piston rings and into the engine. Every stroke of the piston, you are introducing petrol, moisture, acid and carbon into the tiny 4-5L capacity of engine oil. All these contaminants has nowhere to go and resides in the engine oil. The oil filter is only good to remove large particles of contaminants but not things like water and acid.

I change my full syn every 5000km not because the oil is dead but the oil is dirty. Here are some numbers to crunch.. if you drive 5000km at 100km/h, at 3000rpm, it will take you 50 hours to complete. 50 x 60 x 3000 x 2 (each rpm is 2 strokes, up and down) = 18,000,000 strokes. How much junk do you think would have gone past the piston rings after 18 million strokes up and down? That is only 5000km at a constant speed.

Added: Oh yeah.. I forgot.. that is only for 1 cylinder.. if you have 4 cylinders, multiple that by 4.

This post has been edited by sleepwalker: Apr 25 2012, 02:46 PM

Yes this is reason why, regardless of Mineral or Fully Synthetic, all oil must be changed at the same time. The No.1 myth amongst Malaysian motorist is "Mineral last 5000-km and Synthetic last 10,000-km" nonsense.

thanks for the explanation. i also change my semi-syn regardless when people say it can last 6-7k++ mainly due to contaminants etc. not to mention our proton iswara oil filters these days *SEEMS* to be getting smaller and smaller, no doubt the filtration effects would be lesser

anyways, could you also provide an explanation on why some engine oils will degrade/sluggish/bad performance after x k km(eg: 3k km) while some (regardless of mineral, semi or full syn) can last 5k km easily, or even 10k km for the same exact engine? probably also why some "myths" spread from there on how full syn OCI is 10k km, while mineral 5k/semi syn 7k respectively?

I have thought of that and the only explanation I can come to is, Synthetic oil are simply more slippery so giving you the smooth feel. But we know the reason why we need to change oil is not because it's still slippery but rather the other factors aka contaminant & depletion of additives etc.

Engine oils should not degrade an engine performance unless it is becoming sludge. That is usually caused by the introduction of contaminants and not the breaking down of the engine oil.

In the case of same engine, different rate of engine oil deterioration would be cause by the amount of the additives in those engine oils. The additives in engine oil is providing the primary protection and not the base oil itself. Some engine oils have less additives and will start slugging much earlier than others due to the contaminants.

Broken down engine oil turns watery and not sluggy. I have used the same semi-syn in a 1.3 and then later in a 1.8 turbo. In the 1.3 it was fine.. in the turbo.. after only 2000km, the oil consistency turned to almost water but it was not black or contaminated. However this only applies to a few engines using wrong type of engine oil. The majority drivers out there will not see this happening.

This post has been edited by sleepwalker: Apr 25 2012, 05:32 PM

thanks for the reply.

so with this we can assume that semi syn/full syn oils have more/better additives? and not so much the base oil property being better?
or rather instead of "limiting" to oil base property, more towards "expensive" engine oils (regardless of semi/full syn, some examples would be redline/motul/liqui moly/torco) having more/better additives?