is it possible to switch form ordinary mineral oil into synthetic oil for a high millage car engine.?

just change the oil and filter and put the synthetic in, as long as your car doesn't use any oil or leak it you will be fine.

yes, but its a lot easier to just take out a twenty dollar bill and light it on fire every few weeks. :) Just teasing. I think we can assume your high mileage car doesn't use any oil, either through burning it or leaking it? Just think it through a little, in terms of when its likely to start doing either one of those. As the other posts have suggested, synthetic is pricey, so its probably not going to be the more economical option.

Also be sure to figure the true value of your high mileage car and the realistic remaining life. Then do the numbers on synthetic vs regular oil. It might be hard to make a case for the synthetic. But its not impossible. Depends on the details

Dude!! You're putting mineral oil in your car???? Sorry, couldn't resist, and yes, you can switch over from motor oil to synthetic in a high-mileage car when doing a complete oil change. Check out the link for myth-busting on the subject.

the only possible harm is that synthetic oil cleans the engine better and at this point it may do more harm than good. I wouldn't recommend it.

If it isn't broke don't fix it.

like the others said just change it and i run mobil one synthetic in everything i own and never had a engine blow.it is far better oil then conventional oil and all cars and trucks are built to burn some oil even new they use some oil they are made that way...........

I made the switch on my high mileage car without any problems but since my car is burning a little oil, I use less expensive oil to keep it going.

No need to do any special prep, you can switch to and from whenever you like. Just a technicality but it's not mineral oil, that's another name for baby oil.

it is, but i don't recommend it... if by hi mileage you mean a lot of miles, as in over 120k. by then you'll have weak spots in your seals that the mineral oil, because it doesn't clean as well, was hiding with gunk. the synthetic will clean that out and expose your weak spots causing the engine to leak.

Valvoline durablend is rated better then most full synthetics, including mobile 1. it's also a blend. I would use this.

Yes, you can switch at any time and no, you don't have to flush the engine first.