is it okay to switch from regular to synthetic oil when the car has over 100k miles on it? what if the head was rebuilt? a couple people i asked said no because the thicker oil will have sealed any potential leaks and the synthetic would just wash it away. on the other hand, a few people have said no problem, it's a much better oil and won't do any damage. btw, no repost police please, i already searched.

 

I wouldn't.

I have already been down that route and conicidentally, I had to replace my piston rings about 10k miles later.

What is the need for synthetic oil?

 

The bottom line is synthetic costs more and works better for some applications and literally doesn't break down like conventional oil. Really good synthetics like Royal Purple have been proven to help in HP numbers, but in the long run you'd end up paying a sh!t load more.

 

thanks guys...thats all i needed to hear

 

I switched to synthetic at 140k. 50k miles later my engine has consumed far less oil than it did with regular mineral oil and I have developed no problems whatsoever. I don't really buy the stigma that people have against switching to synthetic...if your car is fucked up to begin with, synthetic oil will make it more readily apparent because of the smaller molecular size. However, if everything is in good shape, it should help longevity.

 

i'm right in the middle. my head has about 8k miles on it but my bottom end hasn't been touched(155k miles) and my head gasket is leaking.