Re: Synthetic, semi-synthetic, and ordinary motor oils.

If you're using ordinary motor oils , then you will do oil change every 5kms reading in the Odometer from your Car or more or less 3months , Then using Fully sythetic evry 10kms or sometimes can reach up to 12kms based on manufacturer recomendations as what Fuchs Triton Synthetic 5-50W which now I will start to use before I'm using Mobil 1 0-40W. But i think I still go for 10K Oil Change .
;D

Re: Synthetic, semi-synthetic, and ordinary motor oils.

I've read somewhere that fully synthetic is not advisable for brand new cars and for cars with very high mileage.

Brand new cars will not properly break in with fully synthetic. High mileage cars will just burn off the expensive synthetic oil.

Are these recommendations correct? If so, how many kilometers on the odo before you can start using synthetic?

Re: Synthetic, semi-synthetic, and ordinary motor oils.

If you have car's mileage has already gone through at least 20,000km, you can start using Fully Synthetic Motor oils. Brand new engines need to be broken in before using fully synthetic.

Period between oil changes using Fully Synthetic depends on the oil. Mileage can be used as a reference but not as reliable. Instead, use both mileage and oil color and consistency. When you pull out the dipstick, check the color. If its still light colored then it should still be good. If its very dark and dripping from the dipstick then you need an oil change.

Some high-end synths can actually last more than 10,000kms. Mobil 1 Fully Synthetic is known to last at least 20,000km on a good engine (just remember to change the oil filter every 6,000km-8,000km). But dont expect it to last as long on an engine that has bad cylinders and losing compression.

If you want to go back to using normal oil, you need to do it slowly. You can switch to semi-synth blends but have to do a change at a more closer interval, say 4,000km. You can then move to regular oil after the engine has gone through 2-3 oil changes on semi. I dont recommend this if the engine has been using synths most of its useful life. Best to stick to synths.

Re: Synthetic, semi-synthetic, and ordinary motor oils.

Finally, I found & downloaded a pdf file on Motor Oils and Engine Lubrication and the author says, synthetic oils in new cars do not prevent the wearing-in (breaking-in) of that new engine. He says that this procedure is already done in the factory and with the new car running from the assembly plant to the car depot and on to the dealer itself, this is enough of a break-in period.

Depending on what type of oil placed in the new vehicle, some now like Subaru (which I have now), use synthetic oil, but if it comes w/petroleum based oil, a mere 500 miles (800 kms.) is enough for the switchover, change the oil filter also.

Looks like I'll have to bit the bullet, tighten the belt and continue to use synthetic oil in my Forester.

Q.E.D. 🙂